Can one and a half syringes of Kybella be used for one treatment?

Kybella comes in a vial that can ultimately fill 2 (1 ml) syringes. The amount needed will vary. Keep in mind, Kybella results can take up to 6-8 weeks and usually require a series of treatments. Also, for best results with Kybella, I recommend a combination approach with thermage, ultherapy, exilis. VASER liposuction in combination with ThermiRF is an alternative for contouring the chin, if you're a candidate. I recommend getting a formal evaluation with an expert.

Kybella comes in vials, 2cc per vial, 10mg/cc of deoxycholate.  It does not come in a syringe.  It is drawn up into a syringe prior to injection....so, YES, one can draw up 3cc , the contents of 1-1/2 vials.  This would contain 30mg deoxycholate to treat the fat you are wishing reduced.
Alternatively, you could treat the fat with CoolSculpting, or the original formula of Kybella (mesolipotherapy, which is generally 42mg/cc of deoxycholate, and considerably less expensive than Kybella), or with Ultherapy (microfocused ultrasound, using a transducer that targets the subcutaneous fat).  Liposuction and surgery are other options, too.
Going to Groupon for cosmetic procedures for a "deal" is like going to LongHorn Steakhouse and expecting the quality of steak you paid relatively little for to be equivalent to on at Ruth's Chris or Morton Steakhouse.  It is not going to happen!  
Kybella is extremely overpriced by the distributor, Allergan, and it is therefore going to be expensive to you, the consumer.  If you want a real deal on injectable deoxycholate, the ingredient responsible for killing fat permanently, see someone who injects the original formula.  It is an extremely safe material, and its sole action is to kill fat.  It does not injure any other tissue.  In my own office, for instance, I inject as many as 1200 mg of deoxycholate for $525.