The P250 Sig is modular due to its trigger group. You can pull the trigger group out and placed in the sup-compact, compact, and full size frame platforms. The lowers can be bought for as little as $40.00. The lowers come in 2 sizes per platform, 9mm, 40 cal, 357 Sig and the 45 ACP. The first three calibers fit in one lower and the 45 ACP is a different size lower. They have Caliber X-change kits that come with barrel, recoil spring, magazine, and slide for $369.00. They have all four calibers per platform. You can purchase these accessories online, you just got to look and since they are not a complete gun you can have them shipped directly to your house instead of a FFL dealer. I hope this helps.