If your implying on the conversion kits you can purchase they are a waste of time.. What is your intention other than cost ? You can purchase a 22 pistol of decent to great quality (and even better than that is you go the used route) for the cost of teh conversion kit... then you also get to use the 22lr ammo at a low cost as well in your 22 pistol.
Conversion kits are not the best thing at all.. many times you will need to work kinks out, and then you have specialized magazines, and even at that they will be very picky with ammo after you have done all of this work. The most popular conversion kit are for 1911 frame, and even at that they are highly machined/engineered in order to bring the two together.
The only reason people buy a conversion is like you say for cheaper ammo, but the original intent of this was for practice on your pistol that you were shooting in competition. Another note is that Kimber started building 22 LR pistols on the 1911 frame which was a advantage for those that like the 1911 frame etc...
Now if you really want to get the best bang for the buck load your own rounds, a bit of a learning curve, and some investment, but for pistol ammo you can crank out ammo cheap.. then you have the 9mm round which is really cheap to purchase in bulk even at walmart you can purchase 9mm cheap.
So in my opinion, and experience 22lr conversion kits have a lot of disadvantages, and only one advantage.. You can practice with your own gun is the advantage... disadvantages inaccurate, unreliable, picky with ammo, specialized magazines/parts etc, possible (read probable tuning) by yourself, and very expensive on those that are marketed for accuracy, and expensive enough for those deemed "shoot your pistol much cheaper" with this 22lr conversion kit still in the price of or more than a used Ruger 22LR