Good questions. It would be no more than a guess, but I believe that Daiwa stopped making the 30H and the smaller 27H sometime in the early part of the last decade. I own a pair of the 27H reels, which were my go-to tog reels (along with a Newell-ized Penn 146 Squidder Jr) back before I went all Newell 220. I wonder what part of my basement those reels are sleeping in? I should dig them out and do a refurb - if only to recall the amount of fishies I caught on those oldies.
If you want a comparison, then the 27H would be close to a Penn 145 in capacity and the larger 30H would be roughly along the lines of a Jigmaster 500, or maybe even the slightly larger 112H Special Senator. From what I can recall anyway.
If you want to source one from e-Bay or some other used tackle repository, you can expect to pay around $30-$50 for a real nice example. Still a good choice for bottom fishing and even boat bassing. Very tough reels, very good lock-down drags, parts still available (mostly) from Daiwa, just very heavy reels for their size to hold all day long - relative to today's more current offerings. Especially in omparison to the newer Newells, which now are also considered "Old School." Funny how that works.
Daiwa still produces the larger Sealine reels, and I believe also the very hi-speed 6:1 "Slosh20" (SL20SH), which is still fairly popular in some parts of the country for surfcasting and for casting live bait off the California inshore cattle boats.