@ Seismica
Unless you are dead-set on either a G25 or G27, I would recommend getting
a refurbished DFGT off eBay for around $60. In addition, I would get a Playseat Evolution for around $300. This would be what, around 240 Euros? (Or, you could get a Playseat Classic for around $179, but the reviews I've read said the wheel mount is pretty wobbly/unstable--that combo would be 160 Euros) If you like the DFGT/Playseat combo, but would like to upgrade, you can save the left over money for a G25/G27 for next year. You can then re-sell the DFGT on eBay for about the same amount as you paid for it, so you won't be out any money there. Think of it as a "starter kit" that will get you into racing wheels on the cheap, while at the same time giving you an excellent cockpit that should last for many years to come, and that will accomodate just about any wheel/pedal combo you choose in the future.
Additionally, I think it's possible you could see the price of the G27 come down just a bit between now and the release of GT5.
Perhaps not likely, but possible. As for the G25, I thought it's price would have come down more by now, but who knows, maybe it will also be cheaper in a few months as well. In the meantime, you will have yourself a great sim racing setup "on the cheap", and you will be getting acclimated to using a wheel in the comfort of a purpose-built driving cockpit.
Having a cockpit/racing seat adds tremendously to your enjoyment of games, and I can tell you from experience that the DFGT will perform just as well as a G25, G27 or Fanatec wheel. Within the past seven months, I bought a G25, then a DFGT, sold those to get a Fanatec, sold the Fanatec, and now have a G27. Yeah, I'm an idiot. But I can vouch for the quality and reliability of Logitech wheels. And there is no better value in wheels than the DFGT. To be sure, the G25/G27 offer a better "experience", but they don't offer better performance, at least in my experience.
@ LIL KACHING
The only game where the G27 paddle shifters do not work is GT5 Prologue, at least to my knowledge. They work fine in most other games, and they work in every PC sim I've tried--rFactor, GTR Evo, iRacing, and GTR2. My guess is that they won't ever work in Prologue, because Polyphony can't be bothered to release a small patch for it, and that's what it would take. But from everything I've read, Logitech sounds confident that it will work in GT5. So if you really want to use one of those two wheels right now in Prologue with the paddle shifters, maybe the G25 is the way to go. Both wheels are virtually equal in performance. The main difference I see is that the G27 has slightly stronger force feedback, and a slightly smaller "deadzone" than the G25. But don't let the word deadzone scare you. It's the best way I know to describe the 3 to 5 degrees in the center of the wheel that have a little less feedback than you might want, but you get used to it, and it doesn't really affect the wheel's performance or your laptimes 👍