I had/have really good luck with my Marineland Magnum 350. I way prefer canisters over HOBs. Having said that, with $150 as your budget, I would be more likely to suggest AC110s. In my opinion, you can't go wrong with that filter!
IMHO just save your pennies for a good FX5, be it used or new..for about 250$ you can have one shipped and full of media new. that would be ideal as the oscars grow, so you could save some money for another backup AC110 or what it may be!..
An Eheim 2217 will work but not great as already posted. I would definitely look to get an Eheim first, a Fluval FX5 second, and like CLDarnell said a couple AC110 HOB filters.
I use (2) rena XP3's on my 150g. Weekly water changes, vacuum gravel, are a must if you have oscars and a pleco. They may outgrow your 150, seen oscars 12" and pleco 20"
as of now im thinking of getting a couple ac 110's, but i also found fluval 404 on craigslist for 20 dollars. Its a little over an hour long drive so I dont know if my parents will take me. Anyway, is the 404 a good enough filter for the 150g.