Yes, 93marlin is spot on. I've seen similar Haenels go for upwards of $3k if they are in pristine condition. (there's a Haenel for sale on Guns Int. for $2750. It is a more common 8mm though). Yours doesn't have a straight magazine (loaded via an en bloc clip as originally envisioned on the Commission 1888 Rifle). However, some of those older rifles had the magazine removed and were essentially a single shot rifle for target shooting. Most of the time they also sported fancier sights for such. I can't tell what is under the bottom of your rifle but if it has a magazine, to hold more than one round, it is likely a staggered magazine (aka Mauser or similar). I say this because there's no sign of a rotary magazine release button as seen on Mannlichers with the Schoenauer rotary magazine.
Historically, C.G. Haenel took some leftover actions from 1888 commission rifles and made some very nice sporting rifles out of them pre-WWI. See that article I mentioned in an earlier post. Often referred to colloquially as 1909 Haenels. From just the two pics, and what you've indicated about the caliber, I think this may be one of them.
In general, aside from a person who says "Cool! I want that rifle!" there are some things a collector will consider and it will effect the price offered:
- General condition.
- Does it lock up tight?
- how rare is it? Is it one of a kind?
- Is there a provenance? (i.e. did the Red Baron or Frederick Selous own it etc.)
- has it had major repair work done?
- are the parts all matching and original?
- has it been reblued? has it been correctly reblued (for older rifles: has it been rust blued with the same or similar recipe?). For example, pre-war MS rifles were rust blued but often had the bolt release button nitre blued and the magazine release and bolt retention spring "straw blued". Some also had the bottom trigger plate case hardened. Barreled actions purchased by English gunmakers often had these embellishments standard of what was being offered in the "little Mannlichers" they sold.
- how crisp are the engravings or have they been polished over?
- Is the stock cracked? Has it been refinished? Has it been altered (cut down, or duffel cut etc.)
- Is the butt plate original or has a more modern recoil pad been installed? English gunmaker often put a Silvers pad on the rifles they sold, instead of a trap door, metal butt plate.
- Has the receiver be altered for optics? If so has the front receiver ring been dovetailed or has an addition lug been mounted forward of the receiver ring? Dovetails usually cut into the receiver engraving which is less desirable.
- If optics are installed: Are the optics of the period? Are they clear?
- How does the bore and chamber look? Older rifles were generally subjected to ammunition with corrosive primers of the time. Thus, care had to be taken to religiously clean the rifle before putting it away. Otherwise erosion in the chamber throat is often observed.
These are just some things I can think of off hand. Enjoy your rifle, it is a neat one!