The common vehicle history reports are 99% marketing and are meaningless in terms of protecting you -- READ THE FINE PRINT on the common ones and you will see that all it promises to do is list whatever certain repair shops have told them. NOT ALL SHOPS PARTICIPATE OR REPORT TO THESE SERVICES.
The only way to have confidence that you are not buying trouble at a used car dealer's is to take the car to your OWN, TRUSTED mechanic for a thorough inspection and professional test drive by someone who fixes cars all day. (You may still buy trouble, but you are a lot less likely to do so.)
If you can't afford to have this kind of mechanical inspection of your car by a knowledgeable mechanic before you buy, you can't afford to buy a used car, period.