What LEGO sets/blocks to buy? We plan to buy some lego (up to $200) for a charity that helps homeless children in India. Kids in the charity's homes are of all ages (2-18). Kids are very creative but obviously lack resources. I'm hoping LEGO can be very stimulating for them.

I'm wondering what are the best starter LEGOs that can be played in multiple ways and attract children from all age groups.

I can 1 lb Lego packs from eBay and also some pricey sets at Amazon. I want to get best value for money. I have only 10 days before I fly to India so need to know asap where I can buy from and what.

Many thanks
NG
Different kids are motivated by different kinds of sets. Some kids need directed building to focus them, and so a set with instructions helps them. Other kids just need useful parts.

I'd recommend getting basic bricks to start, something from the Classic line. Or else get something from the Creator line, many of those sets come with instructions for alternate models. This is a good lesson on how the same inventory of pieces can make more than one set. On Lego's Website you can check the set descriptions for Creator sets that are "3 in 1". 

Larger sets will cost more, but the models will be more challenging and will offer more opportunity to build more things (as it's usually easier to build things if you have more pieces).