You can buy Blocknet tokens using any participating coin.
At Bter and Bittrex there will probably only be a BTC:BLOCK pairing.
At Poloniex there will probably be a BTC:BLOCK and NHZ:BLOCK pairing.
At CoinGateway all the other coins will be paired to BLOCK.
After the ITO, only BTC:BLOCK pairings will be available (because it makes no sense for participating coins to trade against the Blocknet when they function to give value to the Blocknet).
How do we buy then with the other participating coins?
Only possible at CoinGateway?
The price of BLOCK is fixed in BTC. But the price of all other participating coins are continously fluctuating against BTC. Furthermore different exchanges have different prices. So how do you determine the BLOCK price in other coins? Will you simply take the market price of each coin at the start date of the ITO and calculate with that? And then take the 10% off of that price?
Will the initial supply of BLOCKs be evenly distributed between the 4 exchanges?
CoinGateway will handle the majority of coins.
The reason for this is that only BLOCK:BTC pairings will persist after the ITO. Exchanges won't be keen to add a pile of new pairings only to remove them shortly afterwards.
For pricing, we'll pick prices of Blocknet tokens at the start time of the ICO based on a recent average (exact algorithm TBD). Then we'll deduct 10%, and put up a sell wall there.
Any discrepancies in price between coins will be arbitraged by traders, and so the market will converge on a 10% discount no matter what coin you use.