I cycle to work but it’s only 3 miles or so and it’s fairly flat. For my bikes I get what we call in the UK either Town Bikes or Hybrid Bikes (I have a Probike Discovery at the moment). They are faster than mountain bikes (I really wouldn’t get a mountain bike unless your commute to work involves a lot of off trail riding!) and sturdier than road racing bikes.
I love my current bike as it is lightish, has a comfortable saddle and it has things like mud guards and a chain guard. The only thing I’d like is a couple more gears (mine only has 3).
As for cost there are 2 routes to go down really; spend more and invest in servicing/repairing the bike or spend less but only bank on it last a year or 2.

Emma

Now I just have to learn how to navigate traffic and not get killed by suburban (both geographic and automotive) drivers.

As for the bike, I only spent ~$200 on my last one, esp. after the 2 prior ones got stolen (despite being locked and in a cage). I treat bikes as commodities now.

Try a non-profit called Our Community Bikes on Main at 17th. They have a good selection of used bikes, and they support a good cause.