The pre-bonsai material is not too bad, price-wise. You can find lots of long- to medium-term projects in 1 gallon and 2 gallon cans. (I stopped buying, since I got too many of those projects already). And the small bonsai are also reasonably priced. But the larger and more mature bonsai are too expensive for me as well. I remember once seing a crab apple bonsai for around $500. I thought I will low-ball them, and offered $250. They started laughing.....
It's a good thing that I didn't buy it, since this year I got much better crab apples at the House of Bonsai (thanks to Si), even cheaper than $250.
They also have some priceless California Juniper, some not for sale - although they could use some styling from one of the young masters. But I can't imagine anybody spending $10,000 for a half-refined California Juniper, in San Gabriel, these days.
But I still shop there for miscellaneous bonsai supplies - for instance, they supplied me with large bags of pumice (1cf) for the last 10 years, they had the best price ($6 a bag). Lately, the price went up to $11, not sure why so much. Also, that's where I buy my oak-leaf mulch (the only place that sells it), which is the best medium for growing beneficial fungi in bonsai soil. They have the best book collection as well (at least in the not so distant past). They also have a really good coarse peat-moss, which I use for my acid-loving plants.
The good thing is that they will never go out of business, since they have a very large customer base, and they have no rent to pay, since they own the place (I think they bought the place for $30,000 back then). Mr Ishii is a great guy to deal with, he is a great bonsai resource. I never understood why he is not involved in any bonsai organization or event. Probably, because running the business takes up all his time.