I've currently backed at 250. 120 of that is for bloodline, which comes with 100 IP. 30 is for a second copy of the game for Rofus (A draw I funded to help promote the game).
The other 100 is for extra IP (1250), giving me 1350 so far. I do plan on adding a little extra now and then once the store is up though. I'll most likely be on over 2600 IP purchased by the time it launches. Potentially more. With any luck I'll get my referral code and some extra points for my earlier efforts promoting the game too :)
In terms of what to spend it on, I didn't want to settle for a "pre-fab" settlement, and instead want to try building from the ground up. I figure this will be a good test case too ie to make sure the approach works.
Looking at the basic 2600 IP, I'll most likely buy:
9 T2 packs (Including plots)
Total 2025
1 2 Story commercial medium building (Tavern)
Total 550
The top floor of the tavern I plan to have as residential.
This all assumes you can operate a tavern in that manner / manage rooms individually for rent etc.
This gives me a base of 9 plots, which will support a village.
If I get more IP rewarded, I'll most likely look at switching some of the T2s to T3 to have the odd small stone commercial building. If I can, the odd small stone cottage would be good too. I'll see what I've got by exposition.