As mentioned, BJ's online will sell to non-members and the $100 card used to be the best value at a 5% discount. Since BJ's updated their online prices and selection there's not much different between them and Sam's Club now, other than BJ's will sell smaller denomination cards (but not as good a discount on those), so whichever is more convenient for most. I keep a chart for myself that was last updated after the November price increase at BJ's.
BJ's Wholesale
Denomination In-Store Price Discount% OnlinePrice Shipping* Discount%
Disney $25.. ........... 23.99 ......... 4% ........ 24.49 ........ 0 .......... 2%
Disney $50.. ........... 47.99 ......... 4% ........ 48.49 ........ 0 .......... 3%
Disney $100. .......... 95.99 ......... 4% ........ 95.99 .......,.0 .......... 4%
Disney 3pk $150 .... 146.99 ......... 2% ...... 143.99 ........ 0 .......... 4%
Disney $500 ...........479.99 ..........4% ...... 479.99 .........5 .......... 3% (when not sold out online, in the 'Adventures & Getaways' sub category)
.....................................................................*per order (may change based on zip?)
Sam's Club
Denomination In-Store Price Discount% OnlinePrice Shipping* Discount%
Disney $25.. ............N/A ............0% ..........N/A ............ .............0%
Disney $50.. ............N/A ............0% ..........N/A ............ .............0%
Disney $100. ...........N/A ............0% ..........N/A ............ .............0%
Disney 3pk $150 ... 144.98 ........3.3% ........142.99 ......0.99 ........4.0%
Disney $500. .........479.98 ........4.0% ........479.99 ......0.99 ........3.8%
.......................................................................*per GC