Or a vee engine. My last vee rebuild was around $2500 with shipping both ways(and the builder ate the cost when it wiped a lobe on the cam on the dyno, and I took a 20/20 crank to save some money too). One of the biggest bike junkyards in the country is only a few hours away, I could save a considerable amount on shipping, could probably scam some free stuff out of them too, they're good guys.
I'm having trouble seeing how this class couldn't be cheaper to run than a vee. Crash damage would clearly cost more, and the shocks would be another expense.