That's where free RDF data hosting comes in. Yes, you can get a triplestore for free. Couple that with a traditional LAMP stack (there is a lot of free LAMP hosting) and you can deploy a Semantic Web application for ¥0 ! A company called Talis is now offering free RDF data hosting, complete with remote SPARQL querying, provided the data is public domain. I hope other companies such as OpenLink will follow. I received an account from Talis' programme manager
♫Leigh Dodds and tried it right away, loading and querying data, with success. They also provide an API that seems quite interesting, but I did not try it yet.
This will be extremely useful to open-source/open-data groups who are run by volunteers and want to enter the Semantic Web scene. In particular, I expect this will lead to an explosion in the number and quality of mashup websites on the Web.