Sometimes I feel like 3 minutes can be a little short for larger bases and golem/giant/healer based armies. I think you should have the option to get battles up to five minutes long. i.e.
TH 10 (cost per search)
1 minute, 650 gold
2 minutes, 800 gold
3 minutes, 1000 gold
4 minutes, 1150 gold
5 minutes, 1400 gold
