I am a 20 year collector of Roman coins of this period, as well as a part time dealer (RomanLode on VCoins: www.vcoins.com). There are some misconceptions here which need to be rectified. First, in Spain, all finds like this belong to the state. Finders must turn them in (not all do - but they stand the chance of running afoul of the law). There is no commission or reward to the finder. Coins of this period (as near as I can tell from the ones I can see, the time period spans approximately 295-307 AD or so) will weigh about 9 g on average. The coins are high grade and despite how they appear in the pictures, most will likely be of very high grade. Coins of this grade will average about $100 apiece for the common ones, and the great majority of them will be common. One of the coins pictured in hand is a rare one of Constantine the Great and should sell for about $600 up to a $1000 depending on grade. BUT - none of these will appear on the market. The Spanish government and the museums and the anti-collector archeologists will not let this happen (unless theft happens).
Stayathomemom's husband, Ron.