For a half-stack at sub $400, I think the Marshall Valvestate 100s might be worth a look. You’d have to be extremely lucky to pick up even a JCM900 and 4×12″ for that money, so a hybrid is a better chance. They’re not bad, either. I’m not American, so I have no idea about the used prices on Randall and such. Another look-at is Carvin. You may spot some of the less-fashionable Fenders, but they’re not exactly grungey. I’d consider a Silverface 100 or 135 well worth checking if it’s in budget.

Feel free to post up some auction listings and I’ll have a look at the specs and advise, FWIW 🙂

LMK, $300-400 for a head and cab isn’t an awful lot. Fender and Marshall are quite different, too. What do want to play and sound like? Does it have to be valve, and would you consider hybrids? If it must be valve, then you’re looking at the less fashionable buys, but some of them are worth having. The dreaded eBay is your best bet, provided you know what to look for and keep patient.