There are some good, affordable mic suggestions in this thread, and I'll add that with upright bass (or any other instrument), hearing the tone of the instrument through a stereo system and hearing the instrument acoustically in a room are two very different things. I'll argue that you do NOT need to capture the full range, pristine, godly tone of the acoustic instrument. Rather, you need to capture a sound that is going to translate through most normal home stereo systems. Toward that end, do not be afraid to experiment with EQ and some dynamic processing (compression), particularly some bandwidth compression on the low end to get the bass to "sit right" in the mix. Many players are anti-compression, but I think they fail to realize that even the best and most recorded bassists were going through all analog gear and there are various instances of subtle compression happening in the signal path from the mic preamp, to the mixing console, to the tape deck.
^^^This is gold. Getting a good recorded sound is a lot like getting a good amplified sound. I used to chase after the "MBOL" ideal, but experience has taught me that - for me, at least - it's a bit of a fool's errand. Even when I manage to get close to it it doesn't sit right in a mix. What I need is something that occupies the right space in an ensemble, whether recorded or live.
Live, when the volume isn't too high, I'm hearing at least equal parts (if not better) acoustic sound with a little reinforcement underneath. At high volumes, it's a different story, and a sound that has some of that "analog-compressor-like" quality to it is a really useful thing that helps glue together the ensemble. Recording is the same way; the "air" that seems to be part of every bassists ideal sound of the bass needs room to breathe. Take that room away, and something more solid is called for.