Please Read "Quick and Dirty Enchantment" on Page 22 of GURPS Magic 4th Ed.
Ok now to some numbers.
In my estimation an average Mage in GURPS would have a Min HT of 10 and at least 5 points of Extra Fatigue (Some would have higher values), this would fit into the formula for a Standard Circle thus, each mage contributing 15 fatigue, takes 75 minutes to recover which equates to 90 point Q&D Enchantments 3 times a day, sometimes a 4th if they feel up to it and are paid a little extra. This will then be the upper limit for standard Circles, at 1 florin per point, this equates to a 90 point enchantment at 90 florin.
Many Circles will increase their power, for a cost, to higher levels with the use of Manastones and Powerstones.
Some average costs
These costs don't take into account effects like High and Very Magic Areas, both are very rare in Balimer, and those that exist are ussually controlled by some powerful group. And Enhancements such as Reduced Fatigue, which really only effect the caster, and since s/he is unlikely to have more than Reduce Fatigue L2 or 3, its not going to effect costs enough to register.
The average group in Balimer will only do 120 point enchantments on a regular basis
Please Read "Slow and Sure Enchanting" on Page 22 of GURPS Magic 4th Ed
S&S Enchanting relies on a steady input of energy over a longer period of time than Q&D does, this allows larger items but takes a lot longer to achieve. As each mage can only contribute 1 fatigue per 8 hour day and a standard group would consist of a Mage with Skill 17 and 2 assistants of skill 15-16, this means on average S&S enchantments are done at a rate of 3 Mage Days per Day ( Divide Energy Cost by 3 to get total days).
However there are large groups in Balien that can reduce the time for S&S Enchantments, they of course cost more than the standard 33 florin per point as they include Master Mages in there Circles
There are three Master Circles in Chaliseton who do S&S Enchanting, needless to say they have a bit of a backlog, and even when they get to your job, it can still take months.