You can easily farm collectors in the 1500s.
I've been TH9 for 4-5 months and have all my defenses maxed. Slowly working on walls and the only thing I've used the entire time is BAM raids (Barb, Archer, Minions) or BotS raids (Balloon and Minions). You can get away with just using barbs and archers and raid anything between 150-200k commonly. Maybe 100k if you think it's worth it.
Just make sure to keep your trophies within that range and don't dip below 1450 or so. I personally never dropped below 1500 and was able to generally farm a million gold an hour or every 2 hours on a really bad day.
This is my base, that thing was built purely in the 1500s. I crawled up to 2k or so for DE raiding.
