A new/vintage audio store? A couple of thoughts come to mind:
First, if you're not in a very urban setting, then you may need more than a simple webpage to reach enough of a market to sustain a business. You should consider something that will allow you to show your vintage gear to a wider market.
Second, if you're doing vintage, you're going to need some really good service capabilities. Most vintage gear, being 20-30 years old, needs quite a lot of parts replacement (caps, in particular). Most folk buying vintage (from other than Goodwill) want to know its been refurbished to original specs. Your business plan should include the sizable capital outlay it will take to equip a shop to handle all that.
Third, selling new and vintage together is tough. If you have the right vintage gear, fully refurbished, it will sound close to the new gear, and cost a lot less. The better a tech you are, the less difference there will be. The two seem to compete with each other. Whether there's more of a competition than between any similar gear is a mystery that could prove expensive.
All that said, I like the idea, and wish you the best of luck with it!