Best budget integrated choices

If you like the Sugden sound, a used Exposure or Naim may work for you.  I would stick with a British amp and sound.  I agree with paraneer  save up for the amp you want, otherwise you will not be happy :) Good luck! 

If you can find an Audio Refinement Complete for $500 or less, buy it and stop there. Likewise, if you can find an Arcam Alpha 10 for $300 or less, same thing. Next step up might be a Plinius 8100, 8150 or 8200. Great integrated amps and great used prices. I've owned all of these at one time and like them all. BTW, my current amp is a Rega Elicit-R. Really nice integrated, but about $1750 +/- $250 used today.

Use your Yamaha, save some money. Watch for a Audio Refinement, Arcam A19, NAD 356BEE, or Marantz 8004 or 5 series, or maybe Rouge audio Sphinx. Any could be had for $5-700 depending on model. I had a Audio Refinement in my system ~6 years age and can testify as to how good it is, however those units are now ~15 or more years in age. I would prefer to buy a used amplifier ~5 years old if I intend on keeping it a few years.

My thinking is that amplifiers of recent vintage ~5 years old can be had for ~50% of original cost, ~10 year old ones ~33% of cost. Of course this is not true for the Classic tube amps of the 60s. Many of these are now valued at many times their original retail price, once refurbished.  

I should have said, regarding the amps I mentioned, "and there  are other brand/models one can consider".  The Yamaha S801 is one.