I am truely blessed living here in Donegal..It's pretty standard south of the Thames, unless you happen to live near one of the few southern reservoirs still operating as trout fisheries. There are quite a few small stillwater trout fisheries within an hour of me, and all cost about the same - i.e. a lot! None are much under thirty five pounds for a two fish limit (which can easily be reached in half an hour) and those with larger than average fish are somewhat more expensive. A four fish limit can easily set you back upwards of sixty quid. The fish rarely remain in the water long enough to lose their stock-pond reflexes, and in most cases the successful method is to try and elicit a response by moving the 'fly' quite quickly - very rarely will you catch on anything remotely natural, unless there's a good hatch of buzzers and the fish get keyed into them.
It's about as far removed from fishing for wild browns on a river or loch as you can get, but we don't have lochs down here and most of the rivers that support a head of wild browns are either private, or let on a day rod basis at upwards of a hundred pounds a time. Fortunately true wild trout fishing is somewhat more challenging than hoiking out farmed rainbows, but for the less-accomplished, well-heeled fly fisher one get a day on one of the stocked stretches of the classic chalkstreams - Test, Itchen, Kennet - for two or three hundred quid.
There are a few places where fishing for wild trout can be had cheaply, or even for free (I know of a handful in my area) but if just 1% of the fly fishers in the locality knew about them and fished them once a month, they'd soon be in decline. They certainly couldn't provide reliable and comfortable fly fishing for everyone who wanted it. Hence the success of the small stillwaters, which probably do look like a rip-off to those who, by geographical advantage, are able to avail themselves of good trout fishing at nominal expense.
Like most things, supply and demand dictate the cost, if not the value.