OP, you need to understand that "high end" on Sniper's Hide means $3000 - $3500 and up. "Midrange" starts at maybe $1000-1200. Some people will say there is no way they would put an expensive scope on a .22... but the reality is, for rifles used in competition, the turrets (especially elevation) are going to get cranked around a lot more than is usually the case on centerfire rifles - e.g., more wear.
What will you do with the rifle? What do you require of it? If all you want to do is plink at tin cans with bucket'a'bullets bulk ammo, that Diamondback might do fine, as long as you don't expect great precision in accuracy or tracking. Also, keep in mind that a $3000 scope is not going to make $3 per box ammo shoot bugholes. If you look in the Rimfire section here, you will find many, many threads about accuracy of ammo costing from about $3.50 per 50-round box up to $20+ for 50 rounds.
With a $750 budget, you can get into decent glass for a .22. Recommend you check with one of the SH sponsoring vendors via telephone for advice. There is a gold mine of info on precision shooting with .22s as well as centerfire here on SH. Dig in!