geez. I bought 2 18"x8" “scrap” pieces from rainbow fins for $25, shipping included. I would just make a panel, using the jack method or similar to what paul described if I was in your position. In addition to saving you a boatload, you could alternate the pigment in the resin every 5 layers and really easily be able to get the quick rough foil.
Laying up your own stack is no big deal if you have glass around.
A 6 oz layer is 0.01 inches thick, make sure to roll between layers. I don’t think you will gain very much by using a car jack.
If you want G10, it is cheaper to roll your own, use a high modulus epoxy with standard glass, because that is all G10 is anyway.
From Resin Research the appropriate epoxy would be 2050. The standard laminating epoxy resins are all specially formulated to be soft like polyester resin which is more suitable for laminating. If you want stiff fins, though, you can use the high modulus epoxy. Otherwise I would stick with poly resin, it is faster to kick.
You can buy G10 sheets from lots of standard industrial suppliers. I use McMaster-Carr a lot. But it is not cheap.Cheaper to roll your own,and then you can make them any color you like.
For cutting out G10, use blades made for cutting steel, and use 3 teeth per the thickness of the part. In other words, for cutting out quarter inch panels, use 12 teeth per inch.
Material cost for thruster fins…its been a little while… A 12"x12" G10 plate is around $30. That’s roughly 4 fins’ worth. Probably a little more than half that if you make your own (and don’t screw it up). I would always lay up 6 inchx18" plates for convenience when I cut out the fin templates prior to foiling. If you email me I can send you some templates, I did all mine on 1 inch grids for design purposes, but you should be able to print them and use them for your own fins.
HTH.