Bill, when i first started i taught myself to cast, and as you said you pick up a lot bad habits along the way...i did get better and better as time when by , but stopping those bad habits gets harder and harder as well as time passes....
It a lot easier to learn the right way the first time and definately is worth the small outlay, really it is an investment, the time and money you invest in casting lesson pays dividends in four fold on the water... You'll be casting better and in turn hooking more fish ,and you won't be worrying about the wind knots so much..
I took a lesson from Harro, and boy did i wish i had taken it earlier.. Rod Harrison is a great guy , who's down to earth, and really know his stuff when it comes to casting, hooking and catching fish.
I definately reccommend him .
Poony