I've been servicing my Gold TDI for the last couple of years. It's not that hard, you just have to be confident about jacking up your car and knowing where to place the support jacks whilst your draining the oil. The fuel filter, air filter and cabin filters are all easy to do, swapping your tyre's around is pain in the back side though especially when you have to do it by hand but it allows you to get a good look at your brake discs and pads and see if they need replacing.
For me to do a full service would take me about 2-3 hours so call it a morning's work and about £40 in parts (can vary depending on what and how much oil you need but for a TDI Golf a 5 Ltr 5w/30 blend of oil sets me back around £30 for a half decent brand) at a garage I'm looking at leat £150 for a full service or £80/£90 for an oil change, tyres and visual inspection (or whatever it is they do on a small service).