MFJ-822 and MFJ-842 SWR Meter
The 822 is from a ham radio supplier for half the price of the pretty little Shakespeare. You cna find similar "VHF" or "2 meter" SWR meters for $25-50 if you hunt around, even a used one from eBay will be plenty good enough. $100 is plain obscene, there's less than $10 worth of components in one and another ten bucks for the case. Radio Shack used to sell 'em new, might still carry them.
Marine VHF is about 156MHz, anything that says "2 meter amateur radio" will cover it.