How easy would it be to restore this GT Dyno Compe BMX for someone with no restoration experience and How much would you pay for it in its current state?

Rust removal depends on how bad and how deep, if it’s minor, it’s just elbow grease and time, if it’s deep, pitted and possibly bubbling, you can’t do anything about it other than have parts rechromed which is seriously expensive and for this level of bike personally not worth it. Current state sale to a dyno fan maybe $150, to a regular bmx collector, less.