Gtechnic exo ceramic should cost you more than £500 if applied by a pro detailer. To me it's not about the next owner benefiting if and when that is it's about trying to keep the car paintwork looking nice for me now and making it easier to clean regularly. You will also get some benefit come sale time as a car regularly car washed or done by the sponge jockeys at your local supermarket will look worse than a carefully looked after car and will almost definitely get you more, might not be much but it will.
So can you get say 5years from this Gtechnic? And only wash it thereafter. What kit and products do you use, I'm starting from scratch (so to speak) as formerly one bucket micro fibre hand held and leather man!
The exo ceramic has a 7 year guarantee and all I do is wash the car now. I use foam, two bucket wash drying towels, wowo wash mits etc etc, wowo wheel kit etc. Biggest thing is nothing sticks to the paintwork if it's been applied properly and I've also gtechnic protection on the alloys which means brake dust crap doesn't stick either. (Other methods and other products can be used) 
Be aware that Exo and Crystal Serum are two different products but often used together by pro detailers.
Crystal Serum is a ceramic coating that is pro detailer application only and bonds with the paint at substrate level and to remove has to be wet sanded off. Gtechniq state it gives 7 years protection (guaranteed), but as I said on another thread, most enthusiasts have moved onto other cars long before then and never find out if this is the reality, but most detailing manufacturers overstate these things.
Gtechniq Exo is an additional coating that can be applied on top of Crystal Serum (or other coatings) which adds a highly hydrophobic layer on top of the ceramic base coat, and this helps to repel dirt, water etc, and will be the coating that reduces the maintenance element to a good degree. The lifespan of this is 12-18 months, so if you are keeping a car long term then this will need reapplying every other year or so, unlike the Crystal Serum.
If you are looking for a very easy care regime then both the above combined are a great choice and you can effectively just wash and go, or if you want you can refresh now and then with C2v3 or another nano/polymer sealant, every month to 6 weeks. A great option to keep things well protected and relatively low maintenance, just the initial outlay to consider (it's not cheap) and an awareness that the Exo (should you choose it) will need reapplying in the future but that can be done either by a pro detailer or by yourself, unlike Crystal Serum.