That gets right up my nose when people start complaining about prices when I struggle to turn over £100 a day these days, remember idiots, that isn't profit.
So this guy has spent £700 on materials and spent 3 weeks, his rewire has cost him £2200 and if he's notified properly, purchased test exuipment could well be nearer the £3000 mark. Any spark could have saved at least 25% on materials and not spent 3 weeks doing the job and notified it and the guy wouldn't have lost 3 weeks income.
The guy wont post pictures of his work now as he knows it's sub standard and he knows he has dig himself a huge hole. Either will remain an illegal install and be untested and possibly dangerous, or retrospective building control will get involved, a couple of hundred quid to them and exposing all of the wiring and then redecoration afterwards, eitherway penny smart and pund foolish.
Always remember, it costs me, and I suspect almost any of the sparks that can self certify £1.50 + VAT to notify building control, it will cost an unqualified (incompetent) and/or unregistered (maybe competent) person maybe a couple of hundred, and even then the LA will make you get the wiring tested by a third person at the DIYers cost.
If you are serious about DIYing and saving money you should get a good electrician on board from the start, before you do anything. The electrician can design the circuits so you know the correct sized cables to install and give you some good pointers of where and how to run the cables, where to drill through joinst, how deep walls can safely be channelled out, the list goes on. Then he or she can pop back and see all of the wiring running through joists, clipped in chases and mounting of accessories before it is all covered up, with a job lot of connector blocks you could even do insulation resistance tests on circuits to check the cables are 100%. Once all plastering and painting/decorating has been completed then the sparky can come back and you could do the second fix together although i'm quite fussy about how the cables are dressed into the accessories so would prefere to show the DIYer a few before cracking on. The sparky can install the consumer unit and complete all the testing, or you could do it together, it is quicker to do some of the testing with two people.
Slapping it all in and hoping for the best is the stupidest thing anyone can do. It is only going to end in tears, costing more money or having an install that never gets tested so could be dangerous. If it is dangerous and your competency comes into question, the only way you can prove competence is by having qualifications.