Or something small and simple...
316 stainless bolts about 30% of DISCOUNT marine store price when bought at my local fastener supply place (bigger range too)
Monel pop rivets. DISCOUNT marine store charges $5.80 for bag of 6 or 8...Local fastener place charges $43 per 1000...but you can buy just one or two of them if you want.
low-loss plated antenna cable. 14 meters at chandlery $75....At Radio Parts $17.50 (Same product, same brand, same part number)