Just a short guide to make sure you know what you're getting into...
Firstly, an N gauge TGV/Eurostar/Thalys set IS a lovely thing to see running round an appropriate layout, but there is something to beware when buying such a set - This ONLY applies to the ORANGE TGV (sncf) SET:
A number of years ago, Lima made a TGV set, designed to be added to with separately-purchased add-on coaches. These sets preceded the (far superior) Kato sets. From a photo, they seem most similar - indeed I was fooled and am now lumbered with a 4-car TGV set that doesn't even run.
There are things to look and ask the seller for, to prove what you are buying:
1- It seems obvious, but ensure you get a box. The older, white, cardboard "Kato" box is a very good sign, even if it means that your model may be an older production run. A "folio" style box is good, but Kato sell these separately. I brought my dud in one of these - look for the markings on the box that indentify the contents as a TGV - AVOID anything that says "Train Set Case" - either in a photo or as described by the seller.
2- The Lima model is SLIGHTLY over-scale. compare it to other continental models, you'll see it's too large.
3- A good way to tell them apart is to look (or ask the seller to look) at the pantographs (overhead power collectors). Lima models have metal and sprung pantographs, while Kao models have plastic, unsprung ones. the Lima ones are also too large for the model and appear out of scale.
4- Dead giveaway here - look under any loco or coach or ask the seller to do the same! Unfortunately, this won't show on pictures, but it's something to know and something you can turn around and say "Look here, you said..."(etc). Anyway, Lima and Kato models have 'Lima' or 'Kato' marked under every unit respectively.
5- Look out for 4-car units (loco-coach-coach-loco). Such units are 99% of the time made by Lima. The 1%of the time that they're made by Kato means that the previous owner was less-than-careful with what happened to the other 2 coaches from their 6-car set and as such the set probably isn't worth buying...
I hope this information has been helpful to someone, I hope no-one gets ripped off the way I did. Lima sets are nowhere near the quality of Kato models - Lima locos are powered by a single power bogie, now obsolete in n-gauge standards compard to the flywheel, all-axel-drive mechanisms within Kato models. Lima sets have a single white light in the loco, whilst Kato locos have full direction head and tail lights and are upgradeable to feature full-coach lighting. I'm not claiming that anyone selling a Lima TGV is trying rip anyone off, just as long as the seller is aware of what is being sold and the buyer is aware of what they are bidding on.