The ESN is printed on a sticker on the back of the phone , usually under the battery.
Typical example: http://www.justcellularstore.com/help/CricketActivation.html
Try visiting the independent retailers in your area as I recommended above. Many will have used (maybe repaired) phones available and you will have a source to take it back to if needed.
If you are not sure where, call some of these:
I got your city out of your profile. I am in the business and have resources. In no way is this an endorsement of any of these retailers. I do not even know what products these retailers represent but if you follow up on them I bet more than one of them can meet your needs.
Wireless Park of McHenry
3815 W. Elm St
McHenry, IL 60050
(815) 363-9933
CallPlan4U Inc
309 Crestwood Ave
McHenry, IL 60051
(815) 349-5640
Activation Point
525 Auburn Dr
Island Lake, IL 60042
(847) 487-7300
Air 1 Wireless Inc.
2450 Us Rte 12 Ste F
Spring Grove, IL 60081
(815) 675-2477
The Cell Shop
2214 N Rte 12
Spring Grove, IL 60081
(815) 419-1157
LuzCom
223 N. Cedar Lake
Round Lake, IL 60073
(847) 548-4000