Whats a good slave flash

I'm looking for one with a built in optical sensor to go along with my 430ex... thank you

There are a few units that I know of that have a built-in slave sensor and adjustable manual mode (which is also pretty important). These would include the Sigma EF-530 DG Super and the Promaster 7500DX. I'm sure there are others. Available on the used market is the Nikon SB-26. The Nikon SB-800 could also be used but it's awfully pricey for this purpose.

While it's handy to have a built-in slave sensor, it's nearly as simple (and generally cheaper) to attach a slave sensor to almost any old flash unit. Slave sensors are available that connect via PC connection or hotshoe (or both), and can be found for $10 to $40. Please note that generally speaking, Canon EX Series Speedlites don't work properly when connected to optical slaves. I have a couple units, including a Sunpak 383, that have hotshoe-type slaves attached to them all the time.

More details in this thread:
https://photography-on-the.net/forum/showthre​ad.php?t=308108

One other possible option: Maybe look for a used 550EX to use as master with the 430EX as slave, using Canon's wireless flash system. This would give you the additional option of E-TTL mode and ratios you can adjust on the master.

I'd love to have a 550 but my wallet told me no...

Well if you don't have the budget for a used 550EX then probably the Sigma and Promaster will be out of range, too. They're both upwards of $200. I don't know what the SB-26 is going for nowadays, but the Strobist crowd has created quite a demand for them so bargains are hard to come by.

Im thinking the sunpak 383 with an optical shoe. Any advice on it?

It works for me!

But if you need advice you'll need to be more specific. From what I've read, even the cheap optical slaves available on E-Bay seem to work fine. If you go with a hotshoe type slave, be sure it has a threaded hole in the bottom for mounting. Not always necessary but it comes in handy sometimes. Wein makes some good slave that are built strong enough you can drive a truck over them. Avoid the "digital slaves."