I no longer have my part-loan - but I used to pay £25/week for 3 days a week. He was stabled DIY at a yard with good amenities - indoor and outdoor schools, excellent hacking and on the doorstep of the beach. I had full responsibility of him on my days - which during winter months when he was in including turn out, bring in, muck out, nets, feeds, water, grooming, exercise. During the summer it was a lot easier as he was out 24/7 and it wasn't as important whether he was exercised as much.
He was a very active 21 year old (who was surprisingly a handful for his age). Because of this there were certain restrictions - I couldn't gallop him or do much jumping (just pop the occasional low fence).
I think you need to take into consideration all the factors on offer before arriving at the final price. If I had been paying half the costs of livery and shoes it would have worked out way too expensive when compared against what else is available for part loan.
Hope this helps.