Mouser, Jameco & Digikey carry Omron basic (=snap) switches.

http://www.mouser.com/?Ne=300&handler=data.listcategory&crc=true&N=65302+6530000\
0&Ns=SField
http://www.jameco.com/webapp/wcs/stores/servlet/CatalogSearchResultView?langId=-\
1&storeId=10001&catalogId=10001&searchType=k&searchValue=omron&categoryId=354075
http://www.digikey.com/

Some Omron switches that should work:

D2F-01FL-D3
D2F-01FL-D
D2F-01FL3-D3
D2F-01FL3-D
.5" long; 100ma, FL means straight lever, 25gf; FL3 means simulated
roller, 40gf; D3 means solder terminals; D means "compact solder
terminals." The D2F spec page is
http://www.omron.com/ecb/products/sw/13/d2f.html


The SS models take a very light force; I think these will be my next
purchase:

SS-01GL-E 8gf, solder terminals, straight lever
SS-01GL-ED 8gf, pcb terminals, straight lever
SS-01GL-F 16gf, solder terminals, straight lever
SS-01GL-FD 16gf, pcb terminals, straight lever
SS-01GL13-E 8gf, solder terminals, simulated roller
SS-01GL13-ED 8gf, pcb terminals, simulated roller
SS-01GL13-F 16gf, solder terminals, simulated roller
SS-01GL13-FD 16gf, pcb terminals, simulated roller
these are normally SPDT, SPST-NO is OK too but not SPST-NC; 19.8mm
long, 100ma The SS spec page is
http://www.omron.com/ecb/products/sw/12/ss.html


There is also the D2S series, spec page at
http://www.omron.com/ecb/products/sw/12/d2s.html
which provides some 18gf models:
D2S-01L-F straight lever, solder terminals
D2S-01L13-F sim. roller, solder terminals