Like Rob said, Son of Sandlar is top of the line for big fancy fantasy boots, but you're spending at least $500 to get anything from them. (The boots are gorgeous, they're high quality, and I think you get a lifetime warranty, but $500.)
House of Andar is a pretty good knock-off. I have a pair from them that was more like $200. Mine came in about half a size too large, though - they have a pretty good return policy, so if you get their boots, consider getting them ahead of time so you can send them back if they don't fit right.
SCAboots.com has good-looking boots for about $150 but I don't know anyone personally that's bought from them.
That said, combat boots aren't the worst way to go, especially if you dress them up a bit. If you wear greaves (shin armor), gaiters/spats (ankle/shin covers that strap under the boot) or nice boot covers, combat boots can look pretty damn good.