Well, I'm in the "recommend making your own" camp, but I am a bit of a DIYer, and my time's currently worth nothing
A smallish can of RF (from a craft shop, not a magic shop!) costs around £4, Use one red and one blue deck which could be as little as £1 each if you use seconds but is probably around £1.50-£2... so that's £8 max for two decks (either two different coloured IDs or a brainwave and a two colour ID), plus you will have plenty of RF left over to top them up or top up other decks...
So presuming you have a bit of time on your hands and you need to save money (hello, student here...!), I would say it's worth it. But as mentioned, you may be willing to pay the extra few quid to forego the hassle.
My issue is that there are a lot of penny-pinchingly manufacturered decks out there... my deck was only just useable when I got it, and I read many other similar stories, so ultimately the decision to make my own stemmed from an issue of quality. And if you're taking the time and effort to lay the cards on some newspaper and top them up properly, well, you may as well be making your own deck.
I personally wanted a deck I knew I could trust, and if you want something doing...
