Dose not really matter how many products they sell, you still have to do the same work if its 1 or 10000 products,, you can ask them to upload all the images & info to save costs. but i would suggest $5000 is a good ball part figure, with hosting and everything included, that’s how much I charge anyway. If you think that is a lot, a rival local company just finished a video dvd stores site for $25,000 which was down from $55,000 because they scanned in the images of the dvds and wrote the descriptions in hours. If its going to be of real value to the business, increase profits, and be something they are proud of then they will pay good money for it. Do not ever ever under sell your services. Always charge the right amount, you have over heads yourself, rent, equipment, electricity, employee wages, ect.. ect…