Heck at this rate I'll end up with a 30lb pack just for a weekend trip.

That's ok. It is often a good idea to start out with whatever bits and pieces you can scrounge up for your first few trips, augmented by a few purchases of new gear. Very few. The real trick to going lightweight in the beginning is what you leave out of your pack. Novices are subject to a thousand doubts, fears and temptations which all turn into unnecessary stuff to lug along.

After you get some experience under your belt you'll make MUCH more discerning investments in gear than you could at the moment. So, don't fret too much over the gear at first, and choose some short, easy overnights to ease into it.

The real advantage to having the lightest pack possible is that it extends your range by conserving your energy. You can still backpack with a 30 lb pack. I do it often. But my 30 lbs take me for a week, not a weekend. Because you'll be starting with weekends, not weeks, you won't need the absolute lightest pack right away. Carry your 30 lbs, don't overextend yourself by choosing a destination 15 miles up a steep trail and have fun learning the ropes. It's all about getting out there and any way that accomplishes that goal is a good first step.