Hi illyun
Good luck with the move to Dubai! Let me know if you need any help setting up as it can be a bit of a nightmare, but you'll love the lifestyle!
Regarding second hand Golfs over here, I only seen 1 Mk5 GTI advertised. All the owners buy new and seem to be holding onto them. They're more exclusive than Porsches, Ferraris, Lambos etc (well that's what I tell the wife anyway!)
When you move over here you will need your residency visa before you can buy any car. Your company should sort this out in the first couple of months, which will give you plenty of time to get used to the traffic in a lease car before you get your own toy!
New GTIs here are much cheaper than in the UK. You get 2 spec levels - the basic has no sunroof and 17" wheels and is around 97,000 Dirhams (13000 Pounds - I haven't seen one on the roads) and the top level has all the bells and whistles on for 107,000 Dirhams (14,500 Pounds) for the 3 door and 110,000 Dirhams (15,000 Pounds) for the 5 door. The spec list is good - 18" Monzas, Cruise, DSG, flappy paddles, 6 CD stacker, iPod connector, xenon lights, climate control, sunroof, folding heated mirrors, rain sensitive wipers, auto dipping rear view mirror, parking sensors etc etc. Mine has leather, electric and heated seats added on for 117,000 Dirhams (16,000 Pounds) - if you spec it on the vw.co.uk website it's a 28,000 Pound motor, so that's why it is mainly Europeans over here that buy them, and tend to keep hold of them.
The only downside is the choice of colours if you want a car quickly. There is no extra charge for metallic but I've only seen Silver, Black, Red, White and Blue on the road. The dealer always has cars in stock but if you want Steel Grey or something different then there'll be a wait as in the UK.
The buying process is pretty easy with low finance rates. You have to have your residency visa and a bank cheque account, but the finance is then approved within a couple of days. You just need to put down 1000 Dirhams deposit (130 Pounds) and within 5 days the car is insured, registered and you're off. I've got my GTI over 5 years for 320 Pounds a month with the first year's insurance included in the finance.
A quick note on the insurance. For some strange reason only know to Emiratis, a 3 door GTI is considered a "sports car" but a 5 door is considered a "family sedan". The insurance can work out more expensive for the 3 door, and as a result I've only seen 1 3 door Golf in the country.
If you were to buy a car here and then leave in a year or so you'd get virtually all your money back. You'd just need to clear the finance before you leave and job done...