You can probably get an AMEX BRG card (yes it's a business card, but in AMEX's eyes everyone is a sole proprietor business owner) or possibly a personal Gold card with a 50-75K bonus which you can use for a business class one-way with Aeroplan miles surcharge free on any combination of UA, Swiss, Turkish, Brussels or very low surcharges on LOT.

AA miles can get you to PRG on AY, IB or BA as AA doesn't fly there. All of those will wind up with taxes and/or surcharges of $100-$150. IB does not show up online so you would need to search to MAD on aa.com and then look for seats MAD-PRG at britishairways.com.

Also, check your United account as you may have a 50K offer, and Chase frequently matches the 30K bonus to 50K if you ask for it. Check the UA card thread.

Unfortunately a nice clean one-stop award ticket from (PHX?) to PRG doesn't exist except on Delta's seasonal JFK-PRG where award availability is typically awful, and BA where you'd have to pay their ridiculous surcharges. But DL is worth looking at if there happen to be seats for your dates.