A tall man`s mountain bike and 2 bikes for 2 local 5 & 7 year old kids

To the point. I`d like to get the 3 bikes for $150USD if possible. I just returned again to repeat a 4 month stay like I did last year. I`m a senior on a fixed income and I really can`t affor about $200USD for a new men`s geared mountain bike. A local tuk tuk driver also got the impression that I would buy his two young daughters a bike when I was saying I would like to if I could. Last year I used a beater the hotel had but this year I wouldn`t mind getting my own. I`m not worried how it looks, only how well it still works. For the kids.... well, I recall how big a thing it was for me when I was 5 and my grandpa bought me a brand new bike so if I can swing getting them bikes i`d like them to be in decent shape.  It was over $150 USD for the 2 new ones I checked out last March. (I think I`ll need to get helmets also) So, Dear Santa.....