The most inexpensive way to filter beer is through gravity...and time.
The trick is to make sure your brew is done fermenting before racking to the secondary and leaving as much yeast behind as possible.
You can also place the secondary in the fridge so more yeast will fall out in the cold and again, rack as little yeast to the bottling bucket as possible.
The less yeast you transfer the less will make it to the bottle.
I use a nylon net on my primary when I pour my wort in. That keeps all the hops out.
Almost all other "filtering" is done under pressure.