@Prestige maybe you are correct in a way this kit is costly. I won't say overkill and i will give my reasons.
The cheaper solutions you are referring to will probably be a 19dbi cpe http://www.scoopdistribution.co.za/product_info.php/58ghz-19dbi-dual-polarity-cpe-9115-p-1522, take into account that its 19dbi and that foamz would have scanned with 23dbi + grid his signal will drop to +- 74. Previous experience I had with this CPE unit is that in 3 cases where a did a test scan for clients with an AP sxt (keep in mind this is not a highpower sxt) the AP sxt got round about -62 and the 19dbi -70. These results does not make me a big fan of the 19dbi CPE. In fact I will never recommend them over 3km they seem to struggle keeping up with the ccq.
At the end of the day its up to foamz what he wants to buy, bearing in mind that if he buys something that doesn't keep up with the other clients he will be disconnected as to not hold back the sector. I'm not familiar with the area layout maybe you can help him do a scan to another AP where doesn't have to extra expenditures.