As you said: the telomeres are repetitive, so by its nature its not possible to amplify a specific piece out of it, as any primers will have thousands of possibilties to anneal.
May I know which plant species that you are working on? Do you need to estimate the length of your plant's telomere? Or you just need it as FISH probe? If you just need telomere sequence for FISH, then I think you can use telomere repeat (TTTAGGG) alone as primer for PCR. You will get a smear after the PCR amplification. If you need only 1 kb telomere length, then you just need to purify for the agarose gel. We used this primers: Forward, 5'-gggtttagggtttagggt-3'; Reverse, 5'-ccctaaaccctaaaccctaaaccc-3'.
I would suggest that you use biotin-streptavidin first. Digest the DNA, then use biotinylated- prob with repetitive base that you target (e.g: biotin-AGAGAGAGAGA) to isolate only repeat region then add linker, PCR and clone. By doing this you can get for target repetitive region.
But if just want to look for location, primer suggested by Chee How Teo..=)