I'd probably put the money into a new pistol as well I'm not sure how much the barrel would be but threading services usually cost about $90-$120 dollars. But that's not the only downside. Larger well known companies who do this usually only do this once a month or maybe twice a month. They do all their orders all once in a day or days during a month they designate for that. Most state right off the bat turn around is between 3-4 weeks. That's a long time to wait. You could find a local gunsmith that will take the job and do it faster but the cost will likely to go up.
The advantage would be if you needed a more uncommon thread cut for some reason a custom order will give you the ability to get whatever specific threading you want. The most common ones seem to be 1/2x28, 9/16x24, .578x28.
1/2x28 from what I've seen seems to have emerged as the most common. I guess it just comes down to how determined you are to have THAT particular pistol threaded. If it's worth it to you go for it. Me personally I'd buy a new gun if the cost was only $200-300 for a .22 anyway, and perhaps sell the old one to offset that cost at a later time.