I have the opportunity to buy a 6 year old GTI 2500 with a vibra-probe for 450.00 here where I live. It has been used little and looks new with a case and VCR tape. My question is age a factor on these Metal detectors. I noticed the 2500 has been on the market for many years. Have they changed any from the first year production to the ones that are sold today..I don't want to buy it and then find out it is outdated or problems occur after so many years even if the detector has not been used...What is a fair price for this machine and probe? I use a ACE 250 with a sniper coil now and it does a good job but depth is limited.