I have visited Mahabaleshwar many times as my brother was in hostel there.Over the years, it has changed a lot.
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At one time in around 2004 the place was less crowded and less filthy. Now in 2012, the place is very dirty and every where there is plastic and garbage that local authorities do not take care of. In 2004 I do not remember giving any Road Tax or Even Pollution Tax but than you have to give rs 20 per person in Panchgani + in Mahabaleshwar + in Old Mahabaleshwar for hell knows why.Which is not taken from the local people. Moreover, Local authority does not use it for betterment of Tourists...
In 2004 we did not pay even a single paisa for visiting around 8 odd points in mahabaleshwar and Panchgani, but we now have to pay rs 10 for each for just visiting the points that are created by nature not the local authorities...
In 2004, we used to stay in hotels with best of views and services @ 500 to 1500 over the 6 years my brother lived there, now the minimum is rs 2500 for couples+ extra for extra people for just one night and in season and vacation these go facilities and services, (But View is naturally Beautiful).
For a 5 people and 2 nights the expense was rs 22000 rs... Quite expensive given it used to cost just rs 10000 rs in 2006.... In season it will cost you even more lets say around 28000 for just 2 days for 5 people...
Goa in comparison costs much low.... I went for 5 days and it costs around 35000 for 5 people....
Mahabaleshwar is very beautiful place and has very best views, Veena lake is grate, Tapola there is speed boating though it is very far away, Mapro Garden is best for Syrups and even Food is very nice add to it very good Ice creams, nice fish pond, variety of flowers etc, There are around 8 points to visit and easily accessible and will get over in just 4 days. Shopping is not recommended as no variety and Exorbitant pricing... We in Mumbai get better products in cheaper rate...
You also have very low amusement options and karting is very expensive, eg rs 300 for just 4 laps... Compare it with Some of amusement options in Mumbai and near area you have Water Kingdom, Essel World, Tikuji ni Wadi, and many more places you can spend whole day in just rs 1000 and under...
All in all, I suggest Mahabaleshwar for a one time visit and strongly a no no.....