This depends on maturity, breed, but figure 20-30 lbs of hay per day = about a third to half a bale of hay per day. Then you may want to consider "finishing" feeding with some grain (ground corn) and other stuff like mineral blocks. These can get expensive since corn prices are through the roof but you don't need much for one cow. Figure a hundred bucks at least for this.

Not sure what the going rate is for hay is in CO but in OH it ranges between $3 and $5 per bale for decent hay with good clover/alfalfa contents. You want good hay with clover/alfalfa since it is high in protein, calcium, etc.

If you get a weened calf (usually ~3 or 4 months old) you can keep it about a year and a half. Butcher at 18 to 24 months. The beef yield depends on breed. Honestly you should consider getting a bred heifer and keep the cycle going.

You need shelter, constant water supply, Shots could be about $100 or so.. again not sure for here in CO.

Lots of things to think about. I hope this at least gets you going