When considering your next purchase of Tigi products or for that matter anything else on ebay you should ask the following questions, is this seller trustworthy, the products genuine and stock fresh from an authorised supplier and why are these items cheaper than in the shops and if I buy something am I likely to recieve a good standard of service.
ebay have made this a lot easier with feedback and the detailed seller ratings but also take the time to see how long the seller has been established on ebay, the variety of goods they list and volumes that they sell. Chances are if they've traded for some time on ebay and are selling large quantities of various products then these items are likely to be genuine from an authorised source.
The more sucessful the seller the more likely they can work on smaller margins and they are often in a position to negotiate discounts from there suppliers and pass some of these discounts on to buyers to make for some fantastic bargains on ebay.
Volume sellers often have the newest stock as they usually need to replenish stocks more often than the occasional seller.
Finally remember all Tigi sellers on ebay rely on repeat custom so take a look at the sellers feedback to see how many customers have bought again and again, this is a good guide to the level of service they've recieved and you should recieve.