Tripod Conundrums

Oh, how I should have listened to the wise photographers who told me to invest in a good tripod and ballhead from the get-go!

I have a few pressing issues that affect my tripod/head purchase decisions right now:

1. Limited budget. I really can't spend a whole lot of money on a good, professional tripod and head at the moment. I'd like to stay under $100, if possible.

2. I currently have two tripods: one is a cheap retail store tripod and pan-head. It appears that I could remove the existing head and mount another if I wanted to. The other is a 20 year old Slik Universal U212 (at least, that's what the leg says) whose head appears useless to me. However, the tripod itself may be useful. (It was my dad's old tripod that I think he used with a video camera, many moons ago).

I'm thinking of just getting a decent entry level ballhead and using one of the two existing tripods. The cheap tripod is light enough to carry with me hiking in search of birds, but is a bit flimsy. The old tripod looks sturdy as all heck, but weighs a ton and wouldn't work well from a portability standpoint - at least not for hiking.

I'd love to go for a Bogen Manfrotto tripod and head setup, but those run closer to $200 even at the entry level. At the same time, I don't want to spend $100 on something I'll end up throwing in the closet and not using.

I need something that will support at least 6 lbs. My spotting scope weighs close to 4 lbs. My camera weighs a little over a pound, plus the adapter and T-mount. 6 lbs gives me plenty of wiggle room. My cheap Sunpak does support up to 6.6 lbs, so I may be able to use those legs with a new head.

I think a good compromise may be to get an entry level Bogen ballhead and use one of my existing tripods. Then, if the existing tripods don't work out, I can cough up the rest of the cash and get a Manfrotto tripod to go with the ballhead.

Does anybody have any tripod advice for a struggling birder/photographer who wants to do some digiscoping on a budget? :)