Hi, can anyone suggest a place for a solo traveller in the Mission District? Would prefer under $100 and not a hostel. Looked at some other websites and there doesn't seem to be much for that area. Thanks in advance.

Is there a reason you want to stay in the Mission?
There is in fact nothing there other than SRO type places and you don't want that.

Agree with above - for $100/night go on Priceline and get a good hotel in a safe(r) location.

would rather walk back from a bar / club than cab it. but if it's all sro's around there, i may have to re-think it.

Public transportation is very good in San Francisco, and there ARE bars and clubs in areas other than the Mission District.

If you use Priceline, as suggested above, Hotwire or another discount site for a decent hotel in the Union Square area, you can take BART (the local rapid transit) from stations along Market Street to stations along the Mission Street strip, including one at 16th or 17th and Mission and one at 24th or so. You're just minutes away.
For Owl service, use the local transit buses called MUNI.
San Francisco's similar to Toronto or NYC. Everyone uses public transit.
It's best to tend to avoid hotels in the Civic Centre area, which is closer to the Mission District than the Union Sq area.

San Francisco has excellent public transit and is quite compact, so getting back to Union Square or thereabouts even after a night of barhopping is pretty easy. Union Square is also good for transit connections to various tourist-oriented places.
When you take the bus, always get a transfer as it allows you to ride about for at least two hours.