Its all in what your time is worth to you. Raising your own you will be spending much less money than anywhere you can buy f/t. So if you spend 45 minutes a week cleaning tubs you are using 3 hours and 15 minutes a month. Figure out what the cheapest you can buy all your rats for f/t then subtract the amount of $ it cost you to raise your rats per month. Take that number and divide it by 3.25..if that number is not worth more than and hour of your time you should buy your rats.