$70 is very cheap for a website, but if you are doing it for a friend and to get experience then go for it. Just don't expect to earn a decent living charging fees like that.
If you are looking at offering brochure style websites to clients, you should probably learn how to use a CMS such as Wordpress or my favourite, Orckestra (formally Composite C1).
Inevitably your client will want to change content themselves, and "most" business people still don't want to know how to change content themselves. Charging a fee for simply logging in to a website and changing some text is a good way to supplement your income.
As for what technology to learn, that's entirely dependent on who your target market is. For the standard blanket web development you'll a) run into lots of competition and b) be able to code it in whatever stack you like
Personally - My approach is to focus on some kind of niche. Integrations with Xero accounting system have worked well for me, as have NopCommerce customisations.