Ball Joint Question W123

[rmmagow]

Based on an earlier post, I am pretty sure I have a lower ball joint problem in my 83 300d Sedan. I would like to try to confirm this by "lubricating" the joint. I was thinking of trying to clean up as much as possible with brake cleaner, the boots are definitely ripped. I was then wanting to spray in some kind of lubricant as best I can, something that'll kind of work its way down and around the ball joint. What would be best to use, WD40 type stuff, grease, regular oil via an oil squirt can? I just want to lubricate them a bit to see if the creaking goes away or quiets down and will confirm the bad balljoint diagnosis.
How dangerous are bad joints? Car is stable, no shimmy, I cannot feel play wiggling the wheel assembly. I ask because I will most likely not have time to replace these until spring but will be driving the car this winter. I know these are tough to replace, would it be less than say $350 to have an indy take care of them?
Thanks for any advise.