I have been tidying up a few bits on The Greenie and have found some replacement springs for the rear shocks at a very reasonable £30 delivered to the UK from India.

They are slightly different in that they have fewer coils and also have tighter coil pitch to one end.
Inner and outer diameter are within 0.5mm of the originals so no problem there although they are tighter in the grey (gray) plastic protector.
Spring rate feels harder, but I haven't had a chance to take the bike out yet as it's typical UK weather and raining.
Side by side you can easily see the difference, but if you have good original shock with corroded springs it might be a an option.
I can't tell how good the quality is yet other than the chrome on the outer of the spring looks ok but on one of them the chrome on the inner isn't great.
I had a quote of £120 to re-chrome the original springs.
Here's a few pics, first one is the original spring.
     
 

Managed to pop out for an hour of shock testing late yesterday afternoon as the sun was waning.
Stayed on the back roads, no off road riding.
Shocks are definitely stiffer, but aren't really a problem on the road.
They might suit a heavier rider, I'm only 175 pounds.
Anyway, the main thing was I had a chance to get out and enjoy a bit of the autumn sun riding around the countryside. 
  

Do you have a link to the source for those? Seem like a decent price. Should fit the early 125 models as well, possibly the 90/100s too.

Love that year/model as it was the first Yamaha Enduro I got to ride as a kiddo!

Mako, it's my "go to" bike and my favourite to ride on the trails.
Here's the link  
Link to springs on ebay UK
I offered £25 which was accepted with £5 delivery.
Ebay.com has some from different suppliers.