From ecorrado:

I think moving to open-source could help this in the long run, though the initial costs could be similar. If they contract with a oss vendor then they will avoid license costs and in the long run may only need to pay for enhancements they actually want, meaning less large upgrades just to get a small feature.

However, I do think the real solution may require more collaboration or distribution of cost, maybe even a hosted model. I could see similar small libraries pooling resources to fund enhancements that specifically serve their users or pooling together for a combined ILS (with individual interfaces). I think this is similar to some of the stuff Talis is working on (data feeds) and I wouldn’t be surprised if some vendor offers hosted Evergreen or Koha on a subscription model to help save on the costs of buying hardware.