Kit for 5D MKI / EOS 5

[AntiThesis]

Soooo, I've talked myself around and around to the point that I need to get myself some kit for the 5D and EOS 5.

I've got a 50mm f/2.5, a 28-80mm f/3.5-5.6 (non IS, non USM, non great - but free!) and a Sigma 70-300mm f/4-5.6 DG (non APO).
I have a Nissin Di622 (I know), some random tripods, and a bag already so that's not too drastically terrible.

I've also got around R3.5k (not much, I know) to spend on something in the range between 17 and 50mm or therabouts. Any suggestions? I'm primarily interested in Macro, Landcape and some light portrait.

If you've got any convincing arguments for flashes, second body, other random equipment, I'm interested in hearing them too!

I'll make a point of saving up over the year and purchasing something nice once a year if I can so it's not really a huge drag if I don't get a particular piece of kit RIGHT NOW.

This is the only section that seemed to fit - mods, feel free to move if not

[Yogotta B. Kidding]

Simon's 28-135IS dammit.
* Flash 430EX
* more memory

[AntiThesis]

Would but he's sold it

Besides, that would be R3k + R2k

So you'd still recommend the glass over other stuffs then YBK?