I recently bought my 997 and decided to go down the Thule route.
If you are buying new, contact Exeter Roof Racks as they will gladly swap out the foot packs to give you what is required for a level set of bars.
I think I paid about £190 inc 24hrs delivery for the wing bars, foot pack and fixing kit, all with matched locks.
If you go for the split foot pack, you can't have the edge wing bars, although in reality the standard wing bars actually give you a more practical bar space. There is no reason why you couldn't trim the excess bar from each side and refit the end caps if you wanted to make the wing bar solution look more 'sporty'.
In addition to the bars, I bought a pair of Thule Pro Ride 591 bike carriers from an ebay retailer for about £115 delivered. Again, I fitted matching lock barrels to the roof bars, so I need only one key. These fit using the t-track and I can remove and refit them within seconds.
Lastly, I then bought a Thule Ocean 600 narrow roof box. This comes in gloss black and is a half-width relatively short roof box which works perfectly on the 997 and still allows you to fit both the bike carriers on the roof. These are usually £200 delivered, but I got mine for about £150 (including t-track fittings) by ordering it alongside some aero bars for my wife's Honda CRV (which means that the bike carriers and roof box can be switched between cars in minutes using the t-track fittings).
So all up I'm in at around £450 for the lot which isn't a lot less than Porsche quoted me for just the Roof Transport System bars.
A few pics:-