For each 1 Bitcoin, you will get (almost) 1000 Stellar Lumens for free.
That's about 31$ per Bitcoin.
For free. :-)
All you have to do, is register your bitcoin address here
https://www.stellar.org/blog/bitcoin-claim-lumens-2/
Also don't forget the giveaway at ever full moon from Byteball:
https://steemit.com/byteball/@mikelmunich/byteball-bytes-for-free-for-everybody