Taking the link you put in. The Treehouse is 191 pieces, $19.99
At the bottom, I found another Lego set in the same price range. Prince of Persia, Ostrich Race http://www.amazon.com/LEGO-Prince-Pe...ef=pd_sim_t_10 has 169 pieces, reg $19.99 marked down to $17.43
Pirates of Caribbean Fountain of Youth is 128 pcs. (but is also a licensed property) http://www.amazon.com/LEGO-Pirates-C...ef=pd_sim_t_16
Isle de Muerta is 152 pcs. Seems very equivalent.
The Friends sets seem to be more accessory heavy, while other Lego sets will have more minifigs. I expect the minidolls are more costly to produce.