I like the idea of a 2nd hand book shop.
I'd pay the Amazon.com price for a book in decent condition IF it was a book I really wanted, otherwise I'd be looking for 50-70% amazon price.
I don't really care for a bookshop/cafe - but the fact that there's people there with a coffee and donut isn't going to put me off visiting.
The idea of having a website is interesting - although perhaps it's something worth thinking about after the store is established. A website will become much more useful after you have a decent amount of stock.
Take a look at
http://isbndb.com/ - there's a massive amount of data on it which would be really useful if you went with the website approach (or even just for your own administrative reasons.)
It would be quite easy to program a site where you could:
- Enter the ISBN of a 2nd hand book - then automatically add the books details (author, title, synopsis etc) to your site's database for customers to search.
- Calculate a selling price at current market rates, for example 66% of average online retailer price.
- Calculate a buying price for a book, for example 40% of average online retailer price, or 35% of average online retailer price if you already have one other copy of the same title in stock.
You could automate the whole process other than typing in the ISBN.