I'll second the praises for the 880. I have the previous model as well and it is exceptional at that price. If you use the lithium batteries it will last over a year.
With coins you're paying for the raw value of the precious metals and/or for the numismatic value of a coin. The numismatic value is determined by many things like how many are minted, quality of the strike, etc... You are paying for the uniqueness of the silver bullets vs just the weight of the...