If you want useful answers, than please provide some details. Your posts have been absolutely useless so far. You specify that it needs to measure 30 A (RMS? peak?) AC. Are we talking 60 Hz or 50 MHz? What does a Tek 1 GHz differential probe have to do with this? You also don't explain what expensive is. Are you a hobbyist trying to get one for $10? Is this for business with a low budget?
I would either look at current transformers (for low bandwidth), or I might hit eBay for used probes. The Tek P6021 (note that you need the termination or an active amplifier) tends to be quite affordable ($100 or so), but will only do ~10A RMS. The Tek CT-4 is a current transformer that will extend the current range of a probe like the P6021, but only has 20 MHz bandwidth.
Don't be surprised to pay over $1k new (I think a new Tek P6021 might be in that ballpark). These are not mass market items, and manufacturing the ferrite is a fairly complicated process. Now it becomes even more fun if you want to include DC. I believe there are three companies in the world (Tek, Lem and Hioki?) that make current probes from DC to the MHz range, and none of them is very affordable. They're also very fragile and expensive even on the used market.
In the high end it's not unusual to pay as much if not more for the probe than for the scope.