I’m not really sure how available they are around the country but there are a few I like that I can usually find fairly easily around here.
Delicato (CA) had a Shiraz in a box for awhile. It’s been hard for me to find lately. They may have just gotten rid of some excess juice then discontinued it, but it was pretty tasty and priced right. Around $12 or $13 for a 3 Liter bag in a box. (Equal to 4 bottles, so about $3/‘bottle’)
Pepi (Napa Valley [Oakville]) does a decent Shiraz (screw cap.) About $10 or $12 a bottle.
Cambria and Eberle Wineries out of SoCal do really nice Syrahs. Same grape, but I’ve found that, CA winemakers at least, tend to use the name Syrah when the wine has a little more spice or zest, and Shiraz when it’s more of a fruity, ready to drink wine. Still, if you like Aussie Shiraz you should definitely give Syrah a shot.
Cambria is about $18-$20 a bottle. Eberle is around $13-$16 a bottle.