Generated Column Not Found

I have this

use dbWebsiteLO
SELECT A.vehicleref,A.manufacturer,A.cvehicle_shortmodtext,A.derivative,min(a.ch) as price,A.capid,B.studioimages,(SELECT term FROM vwAllMatrixWithLombardAndShortModel WHERE vehicleref = a.vehicleref and ch = price) FROM vwAllMatrixWithLombardAndShortModel A
LEFT OUTER JOIN dbPubMatrix..tblCarImages B on A.capid = b.capid
WHERE a.source <> 'LOM' AND a.type = 'car' GROUP BY a.vehicleref,a.manufacturer,a.cvehicle_shortmodtext,a.derivative,a.capid,b.studioimages

I get Invalid column name 'price'. I'm trying to reference the "min(a.ch) as price"

Thanks