Sure, more budget is always better. All. Ways. But if $500 (now it looks like $600, so, more budget

) is the budget, then that's the budget. He's gonna be limited in either amp or cab. Between the 2, the box should get more attention. If he checks local deals, bides his time, is acceptable to older/heavier gear (but still in nice shape mind you), & negotiates well (or at least not poorly), $600 can get the job done pretty well. If the gear is 100% functional, but cosmetically-challenged

, then his bread'll go that much further

. But even if the upped $600 budget is upped slightly again, there'll still be compromises to be made (as there almost always are). Minimum bucks for really current gear that'd work would probably be ~$1200-1300 (something like a used GK MB800 & used 15/6). Short of that (or the older/heavier, although still nice gear I mentioned), his better play is lesser RMS & greater Vd.