In some ways it feels like a (distant) suburb of Denver; there are people who commute from one to the other, though it's about a 40 mile drive. But in other ways it's very isolated. It's politically comparable to Berkley or Austin. It's racially a strong white majority with few hispanics (Denver is over 1/3 hispanic).
As another commenter mentioned, Boulder has intentionally created open space around itself. There's a city ordinance limiting water service to under a certain elevation in order to reduce the attractiveness of building up on the mountainsides. The city owns a huge amount of open space around its borders and allows only very limited, controlled development.
It's actually got a fair bit of tech activity--nothing like top tier cities like SF, NYC, Boston, or even Austin, but for it's size the tech scene is significant.
I don't consider (nor do any of my friends) consider Boulder to be a suburb of Denver. If anything it serves as "the city" to places like Lyons, Longmont, Lafayette and Louisville.
Of relevancy to this article, Longmont approved municipal fiber a year ago.
Everything green is open space.
As a sibling mentioned, the city and the county together own a "green belt" around the city proper that is meant to be permanent. It was actually started in the 50s and has been a great legacy for us nowadays.
Great place just to visit for a few days too!
Land east of Boulder a ways (30 minutes+) can be affordable. Land < 30 minutes from Boulder in the North and East directions can get _very_ expensive. Lots of land west of Boulder in the mountains that can be built on too, but it's also expensive and can be pretty rough regarding roads, fires, floods (as we learned last year), etc....
6 acres of land IN Boulder with one house, water rights, and agricultural zoning has been for sale for a few years for $5m. One of the last parcels like it in the city. Will probably sell soon though for redevelopment.
EDIT: Regarding "cheap" being a subjective term. The neighborhood I rent in is < 10 minutes by bike to downtown and has mostly 1/8th acre single-family-home lots. Recently rebuilt houses with more 2000+ sq. ft. on these lots sell for ~$1m+. There is a lot of money being spent to live in the area.
Fort Collins is another university town but with a lower national profile than Boulder, which again can be a good or bad thing.
Also there's a lot of stuff in Erie and Lafayette which are both fairly close and less expensive. In a Zillow search I found some 4 bedroom houses in Lafayette with an acre in the $400k region, a 20 min drive from being in town.
Once you get there you realize that the two towns are worlds apart. It has a decent tech-scene and extremely beautiful outdoor environment. Good food and beer can also be had very easily.