Price - Don't know, I don't even know what Ian charges for an engine - the wonders of direct debit/wafer biscuits lol
Performance figures - It's difficult to determine which of the engines (let say both are 6hp) are best unless you do back to back testing. At the top level (which most of these engines are designed for) it's a lot to do with the driver and how he/she uses the engine.
I've tried a lot of engines over the years, some good, some not so good but I always go back to Oddified engines because they offer what I need/expect, some people say "I bet Ians engine is better than the ones he does for other people" I know this is not true - I gave him my spare to use at one meeting because someone crashed into his car and broke his engine. Ian was just as quick with my engine as he is with his own.
Things I demand from an engine/tuner
Reliability
Performance
Fuel economy
Good honest service & back up
I get all this from Ian @ Oddified
I wouldn't get this from MMR, DDM, ONB, TS or any other non race proven engine tuner.