Nobody ever calls them high middle low 'voices' - they use terms like 4 voice meaning 4 sets of reeds - then usually referred in more detail configuration as LMMH - Low Middle Middle High (sets of treble reeds).
5 voice is usually LMMMH, but quite rare these days, and not cheap when you find them. Most 3 voice accordions come in LMM but not so common is LMH.
Most accordions in the UK 2nd hand market will have some degree of tremelo/wetness - usually because most either originate in Germany where the trad German tone has some tremelo, and/or because the biggest demand for accordions in the UK are Scottish & Irish - both having some or a lot of tremelo. You want some 'wet' you should be able to find it very easily. You want very wet, you can still find with relative ease. It would be harder to find dry, here.
For a blend of affordability and flexibility LMM would be OK for quite a few years for a beginner.
I'm not sure if I understood your comment correctly in another thread but 96 bass LMMM are also plentiful, and plenty wet to very wet examples there are too.