alpha flashes

I'm looking at getting a relatively inexpensive flash for my a100 (~$200 USD). I'm totally clueless to new flash technology (ie TTL, wireless, etc). I like the idea of wireless. Do the wireless ones work in conjunction with the onboard flash?
Swivel head would be nice, but not necessary.
My intended uses would be indoor photography/general fill in low light & as a macro fill (probably with a 'custom' diffuser like some tissue taped over the flash :D ).

I'm looking at ttl wireless ones such as:
-minolta/sony 36xx series
-sony f42am
-sigma dg 530 super

Anything other models I should be looking at? Anybody used these flashes and can compare?

I don't know too much about those flashes, but I will interject that a swivel head is the most essential feature on an external flash.

Don't go cheap and get something you'll end up dissatisfied with, save a few extra bucks and buy something nice. Or, you'll end up buying the same thing twice.

BM

Of the flashes you listed, I'd say the Sony HVL-F42AM will be your best combination of functionality and value. The 36 series flashes don't swivel, but they are fully compatible otherwise. I actually just purchased a used 36 and I love it, but I mostly just use it as a secondary wireless unit. I have a 56 that is my workhorse flash. Oh and yes all of the flashes are triggered by the pop-up flash when in wireless mode.

I have a Sigma DG500 Super (older version of the 530) and underexposes when mounted on the hot shoe (perfect when used wireless).
Other than that works fine (I already have the habit of compensating +1 or +1.5 when mounted).
It was $ 206 about a year ago.
BTW, I have an A100; I'm not sure if it underexposes with the other cameras.

I use the Minolta 3600 and love it, I'm very pleased with how well it covers macro range, especially at the much slower f-stops. The F42 could only do better, if you could do that, go for it.

And no need for taping tissue paper over the head - all the Minolta/Sony flashes will have a mounted plastic flash diffuser - which does very well.

awesome info. Thanks all! I'll see if I can get a good deal on one with a swivel head.
Hmm, anyone know of a good online store in the UK? good exchange rate going right now:D