Check the serial number chart on this site.  Click the Saophone Museum Tab and scroll down to Serial number.  Then along the top of the chart you will see Conn.  Then scroll down in the Conn listings until you see your serial number under Conn 6M in the year 1934 - 1935.

Serial number indicates it is likely a 1934-35.  However, you would need to post a picture of the bell and the key stack so others people on the forum can confirm the age and model.

Pricing is all over the place.   I suspect that a horn in top shape can get $2,000 - $2,500 when sold by a reputable dealer and in top condition.

It looks like your horn has a nice dent by the serial number.  I’m assuming other problems too.  If your horn needs substantial work (more than just pads), it can cost $500 - $1,500 for repairs.  Would guess that if you tried to sell it as-is, you could probably get around $500 for it. 

Conn’s sound great but they don’t have high resale value.