FYI: Battery technology has practically not advanced in the last 4-5 years.
Meaning, if the original HTC battery could squeeze out 1300mAh, you are not going to get a 3rd party battery with anything over 1500mAh. If they try selling it to you, you know right away they are lying.
Cheap 3rd party batteries can be good, but do expect faster capacity degradation and problems with interfacing with the mobile (e.g. reported capacity/voltage/... incorrect, etc...). Just use common sense and check the reviews before buying.