I taught myself Linux, Apache, PHP and PostgreSQL starting about 6 or 7 years ago. Of course, I was also moderately proficient with C for the 8 or so years before that. But still, I was making $68k in Denver as an intermediate level developer. Our entry level positions started at $35k or $40k. Senior developers were in the $85k to $90k range.
$30,000 is what you make working 9-5 at a gas station in Denver, seriously. It's not like it's East Podunk Idaho, the cost of living is fairly high there, at least in the same range as Chicago, where I now live.
Stick to your guns. Tell them they can have you for less, but only part time, and they need to pony up for benefits. No way would I work the 50+ hours a week they're likely to want from you for that measely a sum. There's lots of construction happening on the I-25 corridor right now, and I knew several guys in my apartment complex there that were making about $40k at that.