How much would you charge? (help me build a quote)

I’ve got a line of a website building job for a potential client overseas. I’ve already got a good reputation with that client for quality work and the relationship I have with them. They want a new website and I’ve stepped forward to build it for them. I’ve done a number of websites for smaller clients with smaller needs and this will be my first big job. I’ve got to make a bid on how much to charge them.

WMPU DEV members and staff, what would you charge?

These are the specs they want for the site:

Their biggest concerns are reliability and stability of the site,along with flexibility to be able to conduct business on the web. Also, selling to several countries, so translation of text is needed althought commerce will be conducted in US dollars only. I am aware of the need to provide SEO … along with integrating their marketing through social media with the website.

Some of the features I know they are looking for is a search feature on the site, a subscription (ie, membership) feature, shopping cart that allows shopper to see what is in the cart as they go through the shopping experience, ability to go back to leave and go back to the cart if necessary to complete the sale, custom graphics of course, a template for a newsletter or blog feature…and more. They would have about 300 products to sell.

All of those things are easy to me to put together. A combination of MarketPress, Gravity Forms, Relevanssi, WPML, SEO solution and some more simple things would build this site. After reading that list, I could instantly see the infrastructure of the site in my head. The biggest hurdle is the management, navigation and browsing of the 300 products. That’s going to be a very time-consuming setup – I couldn’t even begin to figure the number of hours needed to ensure the integrity of every product listing (while bulk import works well, adding featured images is a manual process). Designing a navigable scheme to allow 300 products to be browsable by a visitor is going to be work.

Anyhow, what kind of quote would you give. All the sites I’ve done in the past have taken me between 10-20 hours to build, but they were small. This is larger in scope (largely because of the translations needed and the number of products). I might need a month or two to complete it, but what is that worth in terms of money?

What would you charge for site of that nature?