Spokes, you can always get a "widder electric vest" type thing, like motorcyclists use, wear that, and plug it in at computer desk etc mainly at night when it's cold a human being is either at their computer, their TV, or in a fave chair to read a book. I'm considering just going with an electric blanket this year, I'm in the Bay Area and sure it gets down to freezing, but that's about it.
Just look for drafts around your windows etc and if you insulate, use stuff that's fire marshal approved, read up on it, do it right and use the right stuff. Fire's cool but not cool when it's burning your place up lol.
For me, to keep warm, I just turn all my test equipment on! whoohoo!! Heating by Hewlett-Packard!
Good ultimate cheap warm clothes, get army camoflage pants and wear generic sweats under 'em, those army pants are about the best designed ever, and you can wear salvation army sweats underneath and not have your motion restricted. Very comfy!