Did the end of tenancy cleaners actually come out and view the property when they gave the quotes or did they just give you their standard price? If it was the standard price, it will usually come with the disclaimer "from £XXX". They will usually charge extra for anything other than the lightest of cleans eg if there is a build up of limescale, ingrained dirt on textured tiles, stains that need removing.
If (and it is a big if), the cleaning was necessary and the prices the agency charged were reasonable/in line with market prices, you would have to pay the £430, even if you could have got it done for less. The agency I use charge £16 per hour for one off cleaning. They charge 30 mins per appliance for deep cleaning, 1 hour for deep cleaning a fridge or freezer. So £168 just to clean the basic appliances in a kitchen - a washing machine, tumble dryer, dishwasher, fridge, freezer, oven, hob and extractor. See how it can add up? Carpet cleaning is "from" £46 for 12 x 12 foot room, £46 for a staircase...
Usually the inventories will have a description of the overall cleanliness eg professional clean, good domestic standard etc. Then there will be details of individual items that were dirty eg limescale stained toilet, grease stains, mould on bathroom tiles etc
Decorating isn't necessarily just repainting. I gave examples of things that would come under decorating that you could be liable for earlier eg broken tiles, damaged skirting/plaster, mould/grease/damp stains (that will need treating before painting), peeling paint from humidity. Is there anything other than scuffed/chipped paint in the inventory?