Why is it a good idea to develop?
And what do you mean be "hard to value" undeveloped? You have no idea what it is worth?
I just feel this domain is worth more than $0 that is all, sure to another domainer its probably going to yield very low.
Some research into the term and surrounding terms pulls this: ( Keyword search volume ideas)
[save on groceries]
Medium
720
36
[save on crafts]
Low
49,500
390
[save on foods]
Low
40,500
22
[save on electricity]
High
260
73
[save on craft]
Low
1,000
28
[save on foods memorial centre]
Low
1,600
< 10
[tips on how to save money]
Medium
880
58
[how to save on electricity]
High
320
36
[save on energy]
High
1,600
12
Global TLD sales for "Save on"
SaveOnCars net $1,588 Jul 11 AfternicDLS 3 10 N N
http://SaveOnCars.net DNJournal
SaveOnGroceries com $2,788 Sep 08 AfternicDLS 3 15 N N
http://SaveOnGroceries.com DNJournal
SaveOnGames com $300 Sep 08 Sedo Auction 3 11 N N
http://SaveOnGames.com Sedo
SaveOnCoolGifts com $160 Jun 07 Sedo Auction 4 15 N N
http://SaveOnCoolGifts.com Sedo
SaveOnVista com $70 Feb 07 Sedo Auction 3 11 N N
http://SaveOnVista.com Sedo
SaveOnGolf com $2,400 Sep 06 Afternic 3 10 N N
http://SaveOnGolf.com Afternic
SaveOnCruises com $800 Mar 06 Afternic 3 13 N N
http://SaveOnCruises.com Afternic
SaveOnEnergy net $360 Jul 05 Afternic 3 12 N N
http://SaveOnEnergy.net ThatSoftwareGuy
SaveOnRealEstate com $700 Apr 05 Afternic 4 16 N N
http://SaveOnRealEstate.com ThatSoftwareGuy
SaveOnCrafts com $6,591 Feb 05 Sedo 3 12 N N
http://SaveOnCrafts.com DNJournal
Now I know Australian market is far lower than the US/ global but in my eyes this domain is not worth $0, if you make a site on it and develop some content to show potential that is where I see value.