I see.
Well, The GS150 isn't your only choice. There's this bike:

It has a 'plank' like seat, the fuel tank is 'peanut' styled and it comes with all the reliability and quality one would come to expect from Yamaha. As for concerns regarding performance; it might be a 125cc engine but it has a higher 10.0:1 engine compression ratio compared to GS150's (Which is actually 145cc) 9.0:1.
More compression > powerful combustion > more HP!
And to accommodate the extra heat and friction generated from higher compression ratio; the engines are built with tighter tolerances and better build materials.
Thing is; GS150 has a bad and questionable reputation. There's a reason the likes of Suzuki GD110 and Sprinter have completely disappeared from the scene and you rarely see them on the roads anymore! And there's a reason why The GS150 has practically ZERO resale value! It'll loose 30,000 Rupees worth of value the moment you purchase it!
In the end; it's your money and your bike. And I'm just a stranger who's trying to save your hard-earned cash!
Anyhow, lets wrap this up!
Good luck with your new ride. Ride safe and do invest in a good quality helmet.
Good Day!