OK ......here is another way, from what I read, you want this part fitted rather than DIY.
Here is an Ebay advert for some repair parts, not the parts you need but, these people fit other parts so give them a phone and see if they will put new seals in yours.
euroautopartsau
STEERING RACK BOOT KIT MERCEDES E-CLASS (W210) E 230 (210.037) 06/1995-06/1997 | eBay
So next, another look on EBAY . (Australia )
STEERING RACK GEAR REPAIR KIT GASKET SET MERCEDES E 230 T (210.237) E-CLASS (S21 | eBay ....GASKET REPAIR KIT
I see there is a complete rack there from the UK and cheap posting,but with a different part number??
1997 MERCEDES BENZ E230 W210 STEERING RACK A2104611201 ......I looked at other used racks here in the uk and all had the same part number, is your part number correct??
MORE ..
Items in STEERING REBUILDS AUSTRALIA P/L store on eBay ! More seals.... This seller is in Victoria so you will need to find a garage to do the work for you.
MORE ...
Mercedes-Benz Other Car and Truck Suspension and Steering | eBay
Having studied your leaking rack picture, is it the rack leaking? or are the unions just above the wet patch weeping. Unions will just be probably copper washers which would be very cheap to replace. Get it up on a 4 post or ramps and see exactly where the leak is. Just a thought.....You have had some awful hot weather there of late, has this brought about the leak?
This will keep you keep you going for a bit !
Steve