the best value package holiday seems to be with Inghams for 602 gbp, which departs on a saturday, via Innsbruck ... or for 29 quid extra you could fly with BA, and with the evening departure on the way back, might get an extra morning's skiing (depending on the timing of the bus transfer to the airport) ...
alternatively, to be guaranteed an extra day's skiing, you could do your own package ...
accommodation
there isn't a great choice of accommodation that can be booked online through the town's website (unlike St Anton) ... but they do have a large number of B&Bs, it just seems that you have to contact them directly. their accommodation brochure lists Frühstückspensions from page 36 onwards (ÜF means Bed and Breakfast and HB is half board) and the map grid (planquadrat) helps to find the property - each street/house number combo is highlighted on the town map. to stay in the town itself, ignore all properties with a village name in brackets after the property name (Mathon, Versahl etc.)
one of the good options looks to be Bergfrieden which has 7 twin rooms and is located on the eastern side of town, about 10 mins walk from one of the gondolas, and a few minutes further to another gondola - which goes up to a different part of the ski area. prices start from about 35 euro per person per night ...
travel
the closest airport is INNsbruck, and Easyjet have return flights for around 191 gbp (including 1 piece of luggage). the resort isn't easy to access by train, but is possible with a bus into Innsbruck central station, a train to Landeck-Zams, and then a postbus up to Ischgl - total time would be about two and a half hours. the train part costs around 30 eur return, the postbus presumably another 10 eur each way, and the bus/taxi into Innsbruck station something similar ...
there doesn't seem to be any direct transfer buses, and the 100km journey by taxi for up to 4 people would be 300 eur or 320 eur return, or for up to 8 people it would be 382 eur return ...
another alternative is to fly to Allgäu airport (that well known hub) for 130 gbp (including the cost of a 15kg bag and the rip off credit card fee) from Stansted (dep just after midday) with Ryanair. the journey to Ischgl is about 200km - the 60 quid saving on the flight, could well be eaten up by the double distrance transfer ...
another option is to fly to ZuRicH - flights available from 98 gbp with Easyjet (a bit cheaper to fly back to LUTon) - the 3 hour train (approx 51 gbp) connection to Landeck-Zams (arr 19:21) would be too late for the last postbus up to Ischgl so would require a taxi 68 eur taxi. earlier flights with BA would be 150 gbp (cheaper available for horribly early departures) - so better to get the taxi up the valley ...
DIY price
so the total price (including an extra night's accommodation) via Zurich would be about 440 gbp (assuming the local taxi was shared between 3 pax) ...
flying via Innsbruck and got 4 people sharing a transfer the cost would be very similar to the long winded bus/train/bus option (even cheaper if there were up to eight in a minibus transfer) - and the total price including flights and accommodation would be around 500 gbp ...
Final Thoughts
if there were 4 or more people to share the transfer - Innsbruck seems like the best choice, or if there were just a couple of people, Zurich sounds fine !
