I have seen numerous CRT projectors sold on Ebay and other places within an average range of around $1000-$2000. What type of quality could I expect to from a used CRT for around $2000? Are there any specifications I should look for? Any minimum brightness or scan frequency? Has anyone purchased a used CRT? I find it odd that many of these projectors that are going for around $2000 have retail prices around $20,000.