I would be interested to know what the deal was with the artist, as the non-abstract work would take some time to do, and looks as if it is taken from a basic photoshop programme, whch can distort pictures to get that affect. I would think any uk based artist would have to charge at least £50 to make it viable to produce one of the Monroes at speed by painting over a print or projection, but maybe good planning and economies of scale could bring the price down.
As for the abstracts,I could produce 100 a month for about £25 -£30 each per single 24x24 inch canvas, but the market is tough to get into, lots of ebay artists who churned em out for the past few years have packed up. Open to offers though....