250 bucks for a Barsto conversion barrel & magazines.
Almost forgot, new recoil spring.

 

ditto, I have a 229 in 40 with the BarSto barrel and no locking insert needed.

 

9mm slide/barrel/locking insert...not sure on cost!!

welcome from az.

 

Depending on your purpose, if for personal defense, I would go with a whole 9mm Slide assembly and Magazines, which will cost more, that for just plinking where a 9mm Conversion Barrel can be used along with a Magazine and Recoil Spring.

Price will depend on where you can find a whole 9mm slide assembly plus which version, and the price it carries. Same can be said with conversion Barrels, Bar Sto, and EFK Firedragon are the 2 main vendors for "conversion" Barrels. Conversion Barrels are necessary due to the different diameter of the 9mm Barrel tubes (smaller) than the .357/.40 Barrels.

 

you can have BarSto custom fit the barrel for an additional charge if you sent the gun to them and I do not hesitate carrying my 224, having done that

 

Welcome from Texas.
Depends, You could get an Aftermarket barrel and have it fitted for around $200.00 or purchse a conversion kit for about $450.00.

 

A complete slide will run in the $400-$500 range new, and maybe a little cheaper used.

 

A. Bar-Sto conversion barrel, major downside is if you dont send in the gun to have it fitted you will need to do it yourself. Depending on the gun this could be minutes or hours, took me a few hours with a dremel to fit one to a P229S, YMMV.

B. Complete 9mm slide & 9mm locking block. More expensive, but simple in my experience, get P229-1 mags and you wont have the P226/P228 mag wobble in the wider 40 P229 frame.

 

depends on your gun. MyBarSto barrel dropped right into my 229 with no fitting at all and has worked flawlessly.

 

Op,
Your P229 40 S&W will accept a 357SIG barrel & use the same magazines & recoil spring as used w/ the 40 barrel.

IF,you can find/purchase a P229-1 9mm Cal X Change kit it is a simple top end assy swap.

A P229C/P228 9mm Cal X Change kit would require a locking insert change.

 

I agree with the above post and would drop a .357 Sig barrel in it and call it a day. I know the Legacy P229’s are difficult to find chambered in 9mm. I have one and have yet to have seen another one I could of grabbed. But that gun in .357 Sig would be a tack driver. I have one and can attest. I also have a few in .40 S&W and understand you there. However that’s the cartridge the gun was designed around.

 

When I picked up my older P226 in .40 S&W I bought a complete 9mm slide/barrel assembly. IIRC it was about $400. 9mm magazines were about $35 each - I bought 3. Easy swap right there in the gun port at my range.

 

I just did this in November of last year. I found a new P229 Pro Slide on Gunbroker for $300. I bought a new Sig P229 9mm barrel for $139. The guide rod and spring were both less than $30 each. Then went to GunMagWarehouse.com for MecGar mags, about $34 each. For me, it was worth it, I can carry it either way now. If you buy used, obviously, you'll come out cheaper. I hope this helps, good luck and stay safe.

 

as I suggested-

https://www.sigtalk.com/threads/new-p229-legion-9mm-slide-assembly-complete-optics-ready-from-factory-with-9mm-mags.437481/#post-6213453

 

My EFK was a drop in.

 

My two BarSto barrels dropped in and still fit really tight.