Checking some ads I am running - some have been happily running at 18c /click but are now inactive and the min is now 38c /click which seems like a really big jump.

One aspect is the supposed "quality score"  But how can "portrait artist" be improved in terms of quality?

Anyone know of a way of getting around this default lowest bid amount?

Guessing you mean AdWords, not AdSense?

Lowering the CPC for one term is going to be difficult, the quality score of your landing page may be low - are you getting the ad to link to your home page? - this is usually bad.

My suggestion would be to target 10 to 50 low cost words that combine to give you the same traffic, target each ad to a separate page where you can really work on getting the quality score bumped up.

Increase your max bid for the first few weeks to get your ad shown and the CTR up - this will also increase the quality score of your ad and bring the cost down.

The minimum bid may stay the same, but you may not be charged that much.

Also, don't opt out of the content network (adsense), just bid low - this is because google will penalise you for dropping out of it's most profitable business plan by forcing a higher CPC on the search network

thanks for that - I'll give that approach a whirl