Presumably the quote of £130 was to supply & fit.
I dont think that is too extreme. Engineers have to be paid, overheads have to be paid, VAT has to be paid. ( These will amount to much more than the price of the part) A proper registered Alarm company would not be making an excessive profit at that price.(Also I presume that you would be expecting some kind of warranty - including labour and callout if it went faulty within its guarantee.)