These coins are unofficial 'play money' produced by game manufacturers in England. It's pretty cool to have one of these as a collectible. They are quite inexpensive, unless you can find one in pristine condition. Most sell in the neighborhood of $5 US dollars. I say an uncirculated one go for $100+.
Remember that if you have one of these to sell, a coin dealer will pay less than half of the retail price. There is not much demand since they are not 'real coins' and a hefty mark-up is necessary to offset dealer risk.
The real coin experts on the Internet are over at The Coin Doctor. The doc notes:
'The model coins are essentially under the heading of play money. Originally they were used as counters in card games. The most common of these tokens are brass imitations of guineas and half-guineas of George III. These were made between about 1787 and 1800. Other small brass playing-card counters mix, for example, Victoria with an Imperial German Eagle. The Prince of Wales model half-sovereign was the monopoly money of Victorian children's games.'