I did a pair at home, the power wrap style. Used a regular electric oven,amd put two cookie sheets between the element and the liners. I ended up doing one liner a second time with no ill effect, simply because I learned as I was going along. I have had these 5 years with no issues.
A few tips: cut one or even two pairs of socks into caps for over your toes, and stuff a little in between any toes that you don;'t like smashed together (i.e. if you like some slight wiggle room). Also, pre-heat your shells (I used a hair dryer) so you can pry them open wide enough to put the liner on your foot and then slide it into the boot. You may even want to practice this with your old liners as you need to work fast before things cool down too much. I used a 1" piece of wood under the toes of my boots to make it easier to assume a "natural" ski position that I could hold while everything cooled off. I have orthotics, and put them next to my foot, under my sock. Seems to work OK that way, but YMMV.
These things are probably the best money I ever spent on ski equipment. If you have any reservations, take them to someone who has done these. It's really not difficult, it just has a bit of a learning curve, especially how much room to leave around your toes (and even with an experienced person doing it, you may not like the results the first time and will do them again)