It's not super cheap, but my vote on a kilt for pubs, games, etc. always goes to USA Kilts casual model. They are by far the easiest to take care of, there's a teflon coating(mine still have no stains) and they look good and last. Plus they are made to measure, so they'll fit right! Add in the choices of tartans Rocky offers, and it's really a bargain.

Stillwater Standard or Economy is a good choice as long as bonfires aren't in your plans.

Sportkilt is okay, but by the time you get a few features added in to make it a decent kilt you're in the same price range as the USAK casual anyway.

X-kilt, while you will have to put some work into it, is by far the cheapest. I've made one for as little as 15 bucks when I got materials on a good sale. Most likely you're looking at 30-40 dollars and a couple of evenings work.