Sorry, any way you look at it, 60 pounds is way too much for a game of this quality. This is far from "AAA+", which is what you expect from a gigantic studio production. I can get much more polished, better, more original indie games for far less, too. Unrealistic cost having in mind today's market.
Also saying "for Amiga" is a bit of a stretch. But here we would enter the fight between those who have brand fetish and those of us who actually attach Amiga to a specific type of hardware and I have no energy to fight zealots.
Dreamcast is cool though.
If you want to see what real indie retro gaming of commercial grade should be like, go no further than RGCD http://www.rgcd.co.uk/
I would suggest anyone who is thinking of making a game for a retro machine to work with these awesome fellas.