There aren't very many 4:3 and 5:4 panels available at all beyond 17" these days. You can get largish 1:1 panels for crazy prices though. There's also the posibility of buying a whole 16:9 panel and having it cut to size, but that's not cheap and I'm not sure it's sane either.

A premium would be fine (we'd surely be grumbling still), but no availability is sad. I'm 60% sure the 1up arcade kits are so small because they're scaled to the largest 4:3 monitor they can get.