Wow cool! But why both 24mm and 28mm?
Hard to believe for such an expensive camera but the SD-1 is not full frame, it has 1.5 crop factor so the 24mm effectively becomes a 36mm and the 28mm becomes a 42mm.
And the other more honest answer is I like lenses, I have a 24mm Summilux and a 28mm Summicron as well and while the difference is very slight, it is just fun for the extra variety.
Back to the original topic, are you buying new or used? If you are buying used, the Buy and Sell section in these forums has some pretty good deals, you can also try places like Ben Photo, Prime Photo, Alex Photo, P&G etc. Ben Photo occasionally has parallel import sets that are new and quite a bit cheaper than the local sets. Warranty maybe an issue though.
For new, the 5 major M dealers are Alan Photo, Cathay Photo, Gope's, Max Photo and the Leica Shop at Raffles. Where you buy from really depends on who offers the best price. Depending on how well you know them, the discount can be significant.
Getting the M9 is the easy part. It is the lenses that are going to be a problem. Fast lenses f/2 and faster, meaning the Summicron, Summilux and Noctilux are normally not readily available. Place an order, leave a deposit if possible and wait will be the best option.
The Leica Shop tends to get more stock than the others but their waiting list is also alot longer.
Buying used is a good option, again the B&S section here is a gold mine, do your homework and find out the list price of the lenses because there are some sellers that will sell you a lens above list, nothing wrong with that for those who don't want to wait and are willing to pay a premium.
Lastly, Voightlander lenses are always a decent alternative and you can get that from Chiif.