I know a local BB operator in Cork, and generally he offers his landowners similar terms. Local wireless BB operators generally tend not to have the same returns and/or cash as the mobile operators, so to use them as a comparison would not be fair.
With regards the mast itself, you are probably talking about a small timber pole, with an omi antenna and a point to point link on it that looks more like a satteilite dish, very un-noticeable, and certainly not what most people would consider a mast, but you should check with him to be sure.
In areas where you cant get traditional wired BB, particularly rural areas, wireless would be around the 40 euro pm mark, so that is more of a comparison than 7.5 a month. If you are interested in getting BB, then there is a benefit to you, if you are not, then obvously its no good to you whatsoever. You could ensure that you get the highest availalbe package off of him/her, which would be better for you and make it more worthwhile for you too.
Other points already raised are very valid however, you want to make sure from a legal perspective you are covered, insurance wise, rights of ways, etc.
Wexfordman