I think the best value and power for money will be an Alpha .23 with 0801 pipe.. Even a bit cheaper than your budget maybe. Then spend the extra on a good clutch and some spare plugs..

I don't have the .23, but I have an Argus A52, which is powerful enough as a .21.., and is close to the Alpha .21.. What I like hearing about the Alpha .23 is that it's supposed to have a wicked top-end, in addition to the already major low-end power.. You also always hear about Alphas lasting for many gallons..