By 'decent standard' I mean any model that doesnt look like it was painted by your kid brother on his first sitting...
70% of the RRP on any items that could be considered 'as new', that is - still sealed, or open but undamaged. Blister packs, boxes, or loose complete sets (like complete Saxon Warband, or a complete Foundry set but without its blister)
50% of the RRP for any and all 'assorted' miniatures.
30% of the RRP for any models that dont fall into the 50%. Minis here could be old GW long oop plastics, the sort of models that dont fetch much demand anymore.
You bought a 'Bolt Action, WW2 British Force' from Warlord Games for £39.99. You painted it to an ok, quick uniformed colour, to play a few games at your local club. You then decided you like the look of the Soviets instead. As the models are painted to decent level, I would give you the full RRP - £39.99 in painting credit. You could use this credit on any commission of £80 or higher (based on the 50% rule below)
You picked up three of boxes of Perry Miniatures ACW Cavalry from a show. On reflection, 36 Cavalry are probably more than you need. The boxes are open but the models are still on the sprue.
They have an RRP of £20. You could get a 70% trade value - £14 - for each box.
After an impulse purchase from Ebay, the 'Assorted Dark Age' lot contains several loose miniatures from a mixture of manufacturers - some look like Foundry, a few are Gripping Beast - and you dont have much use for them. They arent complete sets, but the models are still undamaged. For these models I would extend 50% RRP in credit.
Digging around the loft you come across a box of very old Games Workshop plastic Wood Elves. You cant find them listed on the website anymore, but you remember they were around £20. You could get 30% of that in painting credit.
MiC is my only source of income, and often I spend all my working time painting. I sometimes don't get the time to list and sell items I take in trade, or I do list them but cant find a buyer immediately. As I have regular household bills like the rest of folks, 50% trade, and 50% money helps to keep things ticking over.