Hi Peter,
Skill level can be "Very difficult" to acheive a good result in reglazing a tub or sink. Equipment, craftmanship, and material are most important to a good quality and durable finish. You can buy cheap epoxy kit from home center for less than $20 and believe me you will be sorry that you did. Not to mention professional refinisher will charge additional to remove old coating.
For instant, if you car fender got a bad dent. You won't just go to Pepboys and buy touch-up spray can to paint a new fender...you could but the result will not be the same as a professional body shop. Same principle apply to reglazing a tub.
If you are interested in finding out the approx. cost of professional reglazing, visit our company website www.surfacerx.com. There you can find out a lot more informations. Thank you and hope this had answer your questions.