is 30k a lot ...or a little for something like that ?
To me yes

but I guess it's how bad you want something if you don't have the ability to build it yourself...
I went to steam school with the owner and he had one of the main instructors inspect the boiler pre-purchase, and it was near perfect.
Free-lance 1/2 scales can be purchased anywhere from $5k-8K, but any Case 1/2 scales seem to bring premium. This was also built from quality castings so that will raise the price. There is a 1/2 scale case near me for $15K, but it's nowhere near as nice as this one and being that it's advertised as "thin boiler" you might be looking at another $10-12K for a new boiler plus installation.
There is a guy up in northern MN that has many 1/4 scale patterns and he sells the casting kits for $6-8K. He's also been building one for about 2 years now and plans to sell that for $30K.. IMO very high...
You can find decent full scales in the $30-45K range, but I think it's the portability that give these the higher prices. 1/2 scales are a very good size to haul and being the size of a small farm tractor they are very capable of full-size work.