What to do with $150K depends on a lot of factors:
1. What kind of a startup is it? You may be able to build a software product for $150K, but probably not hardware.
2. What kind of people do you need? 2-3 first class engineers creating an innovative product costs very differently from 2-3 college students sitting part time on customer support.
3. Where is the office located? In US $150K may not be as much as in some other countries.
4. What exactly does your startup need? Office space? A lot of storage/traffic? Production unit? Customer support? This one coupon portal startup made $15M exit with no investment, because their expenses were $1K per month on average and the founders paid everything by themselves. An image storage startup paid Amazon Cloud alone $35000 per month and despite receiving six figure investment they went bankrupt. Like I said, it depends on so many things.
Generally speaking, $150K is probably not enough to start hiring full-time employees, but it can indeed be enough to rent office space for the founding team, support the founding team for like a year so that they could concentrate on the startup, hire freelancers and service providers, do a nice marketing campaign, etc.