I own many Sig's. $400 for a good condition P229 is a good price.
However, if you care about the ability to shoot multiple calibers from one gun then consider looking for the .40SW or .357 Sig. This allows you to swap out the barrel and shoot 3 calibers from the same gun, 9mm, .40SW, and .357 sig. (To enable yo to swap barrels you must start with the larger platform of the .40SW and .357 Sig. The 9mm is too narrow for the lager calibers).
These barrels can be had from several different companies such as "Barsto" but I always picked up the spare barrels used off the various gun forums for about 80-100 dollars.
Good luck