I have a set of the "cheap ones". I keep them sharp, and they never give me any trouble. I get consistent accuracy, and quality results every time. I think I paid $30 4 years ago, and only had to replace one bit. I got the 16 piece set.
I've seen the "higher quality" sets, but never used them. Maybe they are that much better, but for the added cost I'll never know. I told myself that when I destroy a particular size bit, I'd replace it with a higher quality brand. Eventualy, I'd have a better set. but I've changed my mind in the mean time. These are doing me just fine.
MLCS has theirs for $44, which seems like a deal assuming they'll cut a repeatable flat bottom hole.
Forstner bits are a staple in my shop. I use them all the time (on white oak, mostly).
As for any purchase, ask yourself this question, "What am I going to use it for, how much punishment will it receive, and how often will I use it?"
Most people use their drill bits a lot less than they could. I personally think this is because not very many of us are willing to blow a wad on quality bits. For some reason, there are certain tools that everyone says "Buy it like it was the last tool you ever planned to purchase" and then other tools that people are willing to settle for Flea Market quality tools.
If you only plan on using your bits in limited situations, then by all means save some money and head down to Harbor Freight. If you plan on using them almost every day, and maybe inventing a few uses for them, then buy a quality set, with a lifetime warranty, and invest in the future.
I personally own a set of forstner and brad point bits from a company called http://www.baddogtools.com and have been very pleased with them. Since these have a lifetime warranty I am not afraid to use them a little harder than most people would. Plus, I never have to sharpen these if I don't want, I just send the dull bit to the company and they sharpen it for me (although both times I have sent in a bit to be sharpened I received a brand new replacement bit).
In the end, it is all up to you, and what you want/need for your uses.