Orbifly for Validation
If you mean getting a validation of a foreign licence to get a US pilot certificate, then you need to find a European based DPE who can check your documents and issue the certificate. Unless Orbifly have an "in-house" examiner, you'd be better cutting out the middle man (ie paying them loads of money) and contacting the DPE yourself.
In the UK, these people are ADAM HOUSE, and TOM HUGHSTON.
As far as similar service to Orbifly, then if you're just talking FAA instruction in your own N-registered airplane, there are a few CFI/IIs like myself who can instruct for US Private/Commercial/Instrument. Many of us don't charge such obscene amounts of money as €550/day either!
Hope that helps, but I'm not sure I totally understood your questions!