What you have are the old Ral Partha 25mm Mechwarriors... The three on the right are "20-900 Mechwarriors: Steiner (3)", while the one on the left is "20-922 Special Forces - Death Squad Assassin: Kurita"
What they are worth is based on a lot of things, most importantly current demand. You could check eBay for sales on similar figures to get an idea, but remember any price you see there is "at that moment". Tomorrow the price you saw today may not even be close (in either direction).
Caz