If you actively fancy building up a bike for the giggles then finding a vintage road frame / forks and converting it to fixed / single speed is fun and straight forward. Otherwise if you're more focussed on getting on the road asap, you should be able to find a used and ok quality bike in budget, something like a used Charge Plug would do the job. Perhaps post a wanted ad in this section and see what turns up, happy hunting!
If you actively fancy building up a bike for the giggles then finding a vintage road frame / forks and converting it to fixed / single speed is fun and straight forward. Otherwise if you're more focussed on getting on the road asap, you should be able to find a used and ok quality bike in budget, something like a used Charge Plug would do the job. Perhaps post a wanted ad in this section and see what turns up, happy hunting!