Now I am in correspondence with Andy.As stated above talk to Mick Solis at Southern GT or Andy Sheldon at Tornado. Both have been producing well known products for a long time with many examples successfully put through the IVA test. I note you say "for a not so big price". The reality is you will need to budget £50-100K to do a decent job. There are many older unfinished kits lurking in peoples garages BUT be very careful. The IVA test is now much different than 10-20 years ago and older kits will have many items which will cause a 'fail'.
Have a good chat with Mick and Andy and they will be very straight with you about the cost and effort involved.