O: Inlight of the facts pointed out by piedpiper ("nonexistant" tonearm & critical VTA issues) perhaps you should ask the seller the condition of the rubber vaccum platter hold-down. From what I understand , that vaccum hold-down is important since small warp-type issues with LPs may have an affect on playback.
FYI: I can verify the following: Bob Dilger had been speaking of the development of the Apollo as early as 1989. The first first offical news release was in 1991. He remarked at the time " it (Apollo) is the culmination of more than 10 years engineering and field experience incorperating Maplenoll's air bearing principals " .
Following L.Walker's 7-12 month association with Maplenoll in early 1990's , The Apollo's price jumped to 6-7K and later to maybe as high as $12,000+ but I haven't viewed any reciepts with that retail price tag . Early Apollo's were to retail between 3-4K.
Its my understanding the air bearings are identical to the entire maplenoll line but I have not examined them. The exceptions to the existing Maplenoll line are in decending order: The plinth , 110 LB. of internally damped plinth constructed of high density acrylic with a 50 LB.lead plate laminate; 70 LB.(stock) record platter w/ record vaccum hold-down; air bearing linear tracking tonearm mounted on an independent, isolated sub-chassis constructed of 3/4" lead plate; a headshell , 2" tonearm and counterweight machined out of a single metal rod and VTA on the fly .
The Apollo was powered by a Maplenoll 40 PSI pump. Other platters were available as option for the early Apollo machines. Changing the height of the platter may mean upgrades to arm manifolds: I do not currenty know of a source for apollo parts. Wish you all the Best.