Want to hire a developer to develop a web app (or SaaS) that allows teachers to create and sell their courses online through the site. Much like ChalkBoard.com
What skills should I be looking for in such a developer? Also, what kind of hosting service should I look for since this app would need to be able to handle many concurrent users. Thank you for your guidance.
From what I can tell (did you really mean www.chalkboard.com ??), You would need a developer with either PHP or ASP aswell as Mysql/Mssql database knowledge.
update:
I googled chalkboard, and it looks like you meant http://www.thechalkboardcatalog.com/, in which case you would want to hire a developer that also had knowledge of e-commerce.
If possible, try to make sure that they know how to secure their sites aswell.
Make sure the dev knows what an SQL injection attack is, and basic ways of preventing it. This Q&A thread (What should a developer know before building a public web site?) will give you more food for thought.
I'd probably say that you would have to see his/her work first. Make sure you like what you see and then check out some of his code. Does he comment in his code, is it well formatted? That tells you a lot about a guy. Also, is he involved with other side projects? If so, which ones. Yeah, I like what I heard from someone else, don't pick someone because they're the cheapest, but don't pass up a good deal either. If someone is trying to cut into the market, he may lower his prices to do so. Hence, sometimes a good deal is a good deal.
But that's just me.
If this will be your primary developer make sure you have him provide you with proof of work that he has completed in the past. Look for someone that has done e-commerce type work and has created an end to end solution. Some people say they have made x, y, and z and then later you find out all they did was the HTML design or the DB work etc... you probably need someone that has done it all in one form or another.
Don't worry so much about technologies but make sure whoever you are hiring will use a technology that they have past experience with so they are not learning it on your dime. You probably don't want to pay for their 'research' assuming you are paying by the hour.
If your looking for a developer to start a start-up with you then all you need is a competent developer that has a passion for learning and a passion for the product the two of you will be producing.