OK, keeping that 111 million/year budget in mind, that gives me two ideas. First up would be a modernized Saturn Patrol Craft, which would look something like this:
Saturn Patrol Ship 3150 Refit
Type: Military Spheriod
Mass: 1,200 tons
Technology Base: Inner Sphere (Advanced)
Introduced: 3150
Mass: 1,200
Battle Value: 2,157
Tech Rating/Availability: D/X-X-X-D
Cost: 114,363,200 C-bills
Fuel: 100 tons (5,000)
Safe Thrust: 5
Maximum Thrust: 8
Heat Sinks: 51
Structural Integrity: 15
Armor
Nose: 165
Sides: 145/145
Aft: 125
Cargo
Bay 1: Cargo (99.5 tons) 2 Doors
Ammunition:
1,200 rounds of Machine Gun ammunition (6 tons)
Escape Pods: 2
Life Boats: 4
Crew: 3 officers, 5 enlisted/non-rated, 7 gunners, 2 passengers, 21 marines
Notes: Mounts 32.5 tons of standard aerospace armor.
Weapons: Capital Attack Values (Standard)
Arc (Heat) Heat SRV MRV LRV ERV Class
Nose (10 Heat)
1 Large Laser 8 1(8) 1(8) 0(0) 0(0) Laser
2 Small Laser 2 1(6) 0(0) 0(0) 0(0) Point Defense
2 Machine Gun 0 0(4) 0(0) 0(0) 0(0) Point Defense
Machine Gun Ammo (200 shots)
RS/LS Fwd (10 Heat)
1 Large Laser 8 1(8) 1(8) 0(0) 0(0) Laser
2 Small Laser 2 1(6) 0(0) 0(0) 0(0) Point Defense
2 Machine Gun 0 0(4) 0(0) 0(0) 0(0) Point Defense
Machine Gun Ammo (200 shots)
RS/LS Aft (10 Heat)
1 Large Laser 8 1(8) 1(8) 0(0) 0(0) Laser
2 Small Laser 2 1(6) 0(0) 0(0) 0(0) Point Defense
2 Machine Gun 0 0(4) 0(0) 0(0) 0(0) Point Defense
Machine Gun Ammo (200 shots)
Aft (10 Heat)
1 Large Laser 8 1(8) 1(8) 0(0) 0(0) Laser
2 Small Laser 2 1(6) 0(0) 0(0) 0(0) Point Defense
2 Machine Gun 0 0(4) 0(0) 0(0) 0(0) Point Defense
Machine Gun Ammo (200 shots)
Features the following design quirks: Improved Communications, Atmospheric Flight Instability
You'll note the use of machine guns and small lasers for point defense. That's because standard AMS is expensive, and laser AMS is even moreso. The prototype AC/5s of the original were swapped for large lasers, which actually are slightly cheaper than the standard AC/5, bringing the price down further. With only 51 standard heat sinks, heat management gets to be interesting, but still viable: you've only got six large lasers to worry about plus your small lasers.
Modernizing the ship freed up quite a bit of tonnage, enough to increase the onboard marines to a full platoon of 21, while also increasing the cargo to 99.5 tons. There was still tonnage left, so I decided to go with adding a tug adapter, rather than capital weaponry, since that was cheaper. If you prefer, a single SCL/2 would bring the price up to 120.78 million, close enough to our annual budget that Niops could theoretically procure one per year. A single Piranha subcapital missile launcher would also fit, and put the price tag at 113.5 million. Similarly, the switch from primitive to standard armor increased the protection by nearly 50%, which is nothing to sneeze at.
Overall, I like how this one came out, and given the Saturn used the Vulture's art, there's even a DropShip mini available for it (though it'll be a bit big).
The other idea I came up with was a Manatee CV: nearly everything is left stock on this one, except the 'Mechs are swapped for ASFs, and the cargo is reduced by 300 tons to add two more ASFs. I've also tacked a couple small lasers on per arc to handle point-defense duties on the cheap:
Manatee CV
Type: Military Spheriod
Mass: 1,900 tons
Technology Base: Inner Sphere (Standard)
Introduced: 3125
Mass: 1,900
Battle Value: 1,553
Tech Rating/Availability: D/X-X-D-D
Cost: 116,174,800 C-bills
Fuel: 135 tons (5,400)
Safe Thrust: 4
Maximum Thrust: 6
Heat Sinks: 129
Structural Integrity: 10
Armor
Nose: 80
Sides: 70/70
Aft: 60
Cargo
Bay 1: Fighter (6) 3 Doors
Bay 2: Cargo (66.5 tons) 1 Door
Ammunition:
None
Escape Pods: 2
Life Boats: 0
Crew: 2 officers, 3 enlisted/non-rated, 6 gunners, 12 bay personnel
Notes: Mounts 15 tons of standard aerospace armor.
Weapons: Capital Attack Values (Standard)
Arc (Heat) Heat SRV MRV LRV ERV Class
Nose (14 Heat)
2 Medium Laser 14 2(18) 1(8) 0(0) 0(0) Laser
1 Large Laser
RS/LS Fwd (16 Heat)
2 Medium Laser 14 2(18) 1(8) 0(0) 0(0) Laser
1 Large Laser
2 Small Laser 2 1(6) 0(0) 0(0) 0(0) Point Defense
RS/LS Aft (16 Heat)
2 Medium Laser 14 2(18) 1(8) 0(0) 0(0) Laser
1 Large Laser
2 Small Laser 2 1(6) 0(0) 0(0) 0(0) Point Defense
Aft (14 Heat)
2 Medium Laser 14 2(18) 1(8) 0(0) 0(0) Laser
1 Large Laser
No tug adapter here because there wasn't the tonnage to work with. In a lot of ways, this is probably a more viable idea, since it's got a bit more reach thanks to the fighters, but while it's only 116 million C-Bills itself, you've also got to procure those six fighters, and it doesn't have the mass to support long-term patrols, with only 135 tons of fuel and 66.5 tons of cargo. On the other hand, it's a Manatee, with 'Mech carrying and cargo carrying versions out there as well, so the Niops Association could basically build one DropShip for all their military needs, and just refit the cargo area based on what any one ship will be doing ('Mech carrier, CV, bulk transport, etc.). While one doesn't exist in canon, a combined-arms transport that holds vehicles and infantry would also be fully possible.
Of course, the biggest issue with either of these is that they're basically speed bumps. In a bigger navy, that might be fine, given they've got bigger assets to respond with once the enemy force has gone over the speed bump. For a smaller nation like Niops, they are the bigger assets: between 3125 and 3150, the beginning of the ilClan era, you're looking at being able to procure 25 of these at most or up to, say, eight larger assault ships like a Union PWS or a Pentagon.
On that list, I think I'd go for the Carrier JumpShips every time... ;)
I was just typing up a reply, but, yeah, that's a valid argument: over 25 years from the start of our exercise to the beginning of the ilClan era, Niops would be able to field 10 Quetzalcoutl class JumpShips, while presumably building regular Scouts for civilian use. That's 12 ASF per Quetzalcoutl, with FTL transport capabilities for them, for a total of 120 ASFs on 10 hulls. With the Manatees, that's 25 DropShips and 150 ASF, but no FTL capabilities, so no quick response. That may not be as big a deal in a system as small as Niops, but it's still worth noting.