Etymotic HF5 is not really similar to the RE-600. The RE-600 has much more bass presence and a more natural/organic midrange, and a much, much larger sound stage. Etymotic HF5 is highly detailed, "clinical", narrow sound stage with very good instrument separation and lower levels of bass and treble.
I have two external 3TB hard drives (3.5" / full size) that I'm not using anymore after upgrading to 4TB. They're both about 3 years old and have been SMART tested as fully functional and in good health. They were purchased for about $115 each previously. One is HGST brand and one is Samsung brand. Both come with appropriate power supply and USB 3.0 cable. Both have been formatted to Windows NTFS prior to shipping. You should easily be able to get another 2-4 years of long...
Best bet is the Etymotic HF5 or ER4. They're ruler-flat, super-extended, and not harsh or recessed at any range. You might find out you don't like that, but you should at least give it a shot. You can probably get an HF series IEM from Etymotic for around $75 used here on the forum or eBay etc.
I had the RE-600 for about a year. It's definitely well-extended treble, but it's very, very recessed. Like 8-12dB short of flat with the rest of the FR. It's not sparkly at all. It's a very detailed and smooth, but quiet, treble range.
Price is firm. Everything is included and in perfect condition. They just don't get as much use as they should! Price includes shipping anywhere in the USA. Add 4% for PayPal or pay as gift/personal. International shipping is fine but it will cost an additional ~$40 USD or so.
Perfect working condition. Beautiful amp with extremely powerful drive-ability. Includes all original accessories. PayPal and USA shipping is included in asking price. If you have any questions or would like to buy, send a PM. Thanks!