To answer your question: Yes I would if the images were important enough ...a national magazine cover or story...or just a photograph that I want the best job done on. I liken it to being a good printer on my home Epsons, but sending out Fine Art photographs to a printer that specializes in that type of printing. I would certainly spend the money if I saw a possible return on that investment in the future.
The retouching field is wide open. There aren't many that specialize in it because of the non-glamourous aspect of sitting behind a computer retouching the images that you know you can shoot better than the guy whose work you are retouching. Tedious and boring if the truth be told...but it CAN be lucrative.
I have a friend that is one of the top photoshop retouchers in the country if not the world...he is in Germany this week with Sports Illustrated retouching photos of Heidi Klum as they are being shot, (lucky bastard) and he charges somewhere in the range of $325 an hour for a complete job. His retouching of a certain celebrity for Playboy got him $45,000 for doing five photos (this was a 2 day rush job that included removing cut off shorts and building a butt. He also retouched the four collector covers for American Photo of a certain celeb who has VERY large thighs that match her VERY large following...you should see those before and afters...LOL
Doing retouching on a local level is quite different and no where near as lucrative, but it is just fine for me. He has recommended to me to charge $50.00 per image for anything under twenty images...over twenty images it is $35.00. I have lowered that price to $40.00 and $25.00 respectfully. Doesn't sound like much, but I am not in his league either...I'm good, but not THAT good. What you don't realize is that the amount of images you do adds up quickly...I just did some retouching of family portraits and billed the client for doing 135 images. You do the math.
The whole point to this is this: In the beginning you have to charge less to get your reputation working...then as you get better (and you will), you charge accordingly...One day you can charge fees like my friend and be able to go out and buy 2 30" Apple Cinema Displays at one time.
I hope this helps...I tend to ramble (ya think!?!?)...LOL Good luck in your career path, and in making a tough decision.