Hello
Couple of comments.
1) You should be able to use Numbers '08 (Numbers v1.0.3) under OS X 10.10. Just remember to apply the following updaters to iWork '08 programmes.
Numbers '08 1.0.3
https://support.apple.com/kb/DL809
Pages '08 3.0.3
https://support.apple.com/kb/DL808
Keynote '08 4.0.4
https://support.apple.com/kb/DL807
2) Once you have Numbers '08 operational under OS X 10.10, you might try exporting Numbers '08 document as Excel document and opening it by Numbers v3. (Note that there's some incompatibilities between Numbers v3 and previous versions, notably sorting behaviours on inter-cell references.)
3) You might obtain iWork '09 DVD package quite cheaply from various sources suth as amazon and ebay. Just remember to apply the following upadater to iWork '09 programmes before running them under OS X 10.10.
iWork 9.3
http://support.apple.com/kb/DL1563
Hope this may help,
H