Thing is, in the modern business world, you need some sort of web presence to attract customers - as a new customer, I'd pass over any number of retailers I couldn't see on the web, unless they're local, in favour of a company who lists products on the 'net. Even then, I shy away from the companies that say "call me for a quote" or "send us an email". Ok, it gives me an opening to negotiate on price, but if they then start saying "the price I offer you is rock bottom" then why don't you put a price online?
The caveat to all that, I think, is that if you're going to bother with web-presence, you need to respond timely to the genuine queries that come in. 2 hours is not unreasonable. I call the time between sending an email and the response "desperation factor" - if it take 5 minutes to get back to you, then they really want your business. If it takes 2 hours - well they want your business, probably too busy to answer a query immediately. If it's 6 hours, well it should have been responded to by then, they might have been busy, but more likely someone was too lazy to respond straight away - a bit ambiguous, but not a bad sign. If it takes more than a day, they're not interested in your business. If it takes a week, then they're a one man band and he's doing it in his spare time and not that bothered.