Me being at amateur in this game need to know where to start.
Start with your road bike set up, select your favourite bullhorn handlebar and work backwards from that to find out what length your prospective lo-pro frame needs to be. Then keep an eye on the classifieds here, on the timetriallingforum and ebay until something in your size comes up. At your budget, you're going to be looking at something UK built since the major Italian brands attract a premium which has no relationship to their quality or scarcity. You should be able to pick up something in any relevant Reynolds tubeset (531, 753, 653 or 853) within your budget. Look through this thread and current projects if you want to identify some names to look for.
Start with your road bike set up, select your favourite bullhorn handlebar and work backwards from that to find out what length your prospective lo-pro frame needs to be. Then keep an eye on the classifieds here, on the timetriallingforum and ebay until something in your size comes up. At your budget, you're going to be looking at something UK built since the major Italian brands attract a premium which has no relationship to their quality or scarcity. You should be able to pick up something in any relevant Reynolds tubeset (531, 753, 653 or 853) within your budget. Look through this thread and current projects if you want to identify some names to look for.