no just dont go overboard, get something resonable price wise because it wont fit by christmas! Wait until hes a big boy before you get him a super duper coat to last him!
I got one for my lurcher at that age because he's more or less hairless - he grew out of it before the end of the first winter! He kept growing until 2 so this winter - his third - is the first he's been able to wear last year's clothes.
Can you find someone with an older dog and score the hand-me-downs? I gave Stan's puppy coats/jumpers to the rescue we got him from and the next outgrown lot to someone with a smaller lurcher.