I built a 1.8m high wall recently capped joints raked out, 4" block on the flat, did the foundation myself, total cost about €90 per metre. Very solid wall, could be done a little cheaper with 9" cavity blocks but the brickies charge you more for laying them (swings and roundabouts).
Also toped a low wall (900mm) with a 1200 mm high fence panel. (picture to follow) Nice job, panels are bolted to the wall, ain't going to move as long as you don't have too long a run, on exposed site would have done it hit and miss with the panels on either side of the wall.
Coincidently the larger wall was to replace a 1.6m high closed picket fence (I actually left about a 3-5 mm gap between boards) I had put up myself using 5x1 treated timber on 4x3 posts. It cost me about 1000 euro in timber to make them, 150 for the mini digger, ? for nails and nail gun and about a weeks work in all. In hindsight I could have bought the panels for the same money but just couldn’t find anybody selling them nearby. Original fence [broken link removed]