.40 ammo seems to be priced about halfway between 9mm and .45ACP in most places.
I used to hate the round but I've really grown to appreciate it and for defensive arms it just might be my favorite caliber. You get relatively affordable practice ammo, 9mm sized platforms, more flexibility in ammo selection than 9mm, more rounds than .45, similar performance to .45 (whether you use gelatin tests, "one shot stops", or FPE as your guide) and it works better out of a short barrel than .45. I think all major calibers do have a place (I don't believe in caliber wars)- 9mm is affordable, is a low recoiling round, the guns hold a lot of rounds, it can be put in small guns, and in good premium ammo it is quite capable; .45ACP is very powerful (for a handgun round), gives more flexibility in ammo selection over 9mm and is relatively low recoiling; .40S&W is the best of both worlds (other than recoil it has the advantages of both rounds, though it is a bit more expensive than 9mm).
The one big disadvantage of .40S&W is that it is the worst of both in recoil. 9mm has a short and sharp recoil impulse due to the high velocity but since it is a small and light round the recoil isn't very heavy. The .45 has a heavy recoil impulse but it is a slow round so the recoil is delivered to your hand much more slowly and so it feels more like a push than a shock. The .40 is a relatively large and heavy bullet so it has the heavy recoil of the .45, but it is also a high velocity handgun round so it has the short (all the recoil hits you at once) and sharp recoil of the 9mm. That does put a lot of people off. Still, in a full-sized and well designed package like the 226 I doubt you'll find it unplesant.