JPW - It sounds like it's too late for my advice, but this could apply to future situations too:
Give them some free time, up front. Give them a place or two to shop & some idea of what to buy. The amount of time you spend on this depends on your relationship - good friends of your parents should get a few hours, friends of your friend's friend should get a few minutes.
After giving them some of your time, explain that you'll be happy to continue to help them for free, in your spare time. Spare time is what comes after family, work, recreation; let them know when you think you might have some. If they would prefer not to wait until then, they can pay your rate.
I do the above for computer stuff, which I earn my living at, & it works for me. YMMV
A seperate issue, especially with family/friends and HT. Make sure they get stuff they can use. I sold my sister-in-law & her husband some of my old stuff; TV, Receiver & DVD Player - and set it all up for them. This was the setup that my wife & 5 year old had no trouble using correctly. To this date all they can do is watch cable & listen to sound from the TV; anything else, like playing a dvd or listening to audio thru the receiver, requires a call to me.