I'm not entirely sure which trends or direction has turned in metal collecting from recent years but can only account my own experience or assumptions.
For my assumptions I'm guessing it's the accessibility of CD. New record player will cost at cheapest $50USD with the average store (at least locally) sells them $75US and up depending on model and quality. After poor luck with 4 record players, getting first two for free, and spending $20 and $25 each on other models..I had NO luck and caved in to buy new model for $90USD which has lasted very well and burned my wax grooves thousands of times in the past year, but I digress.
CD's are common on all modern stereos and generally given their nature are usually cheap. Lately it's changed with the limited CD pressings of 90's DM/BM with units of only 1000 made, even for what's considered 'classic' albums, also the early CD's produced in the 80's when the format was in infancy has grew as well in popularity. I've heard these older and original pressings are always high quality, and also hear that some regarded classics cd-only releases started to pop up in the very late 80's/early 90's when vinyl as a mainstream format began to disappear due to the compact and accessibility of tapes in the mainstream along with CD's rising in popularity due to technological advances, and the format of vinyl began to fall in popularity.
During the 90's vinyl seemed to hit an all time low point from what I've observed as many bands released CD format and tape format exclusively with vinyl being pressed for rare and limited runs. Most mainstream bands hardly did vinyl, or the vinyl versions were pressed in significantly less numbers than the early albums in the 80's so that any vinyl versions at this point are nearly impossible to find. The price of vinyl i assume has also gone way up since the 80's and now costs 2-3 times as much to press in comparison to CD or tapes, so it's also guessed that during the 90's and early 00's when the format was at its low, less bands, especially in the underground looked to doing vinyl.
Now we reach the late 00's and beginning of the 10's and vinyl has begun to resurface as a format. These days it's seen as more a collectors thing, but I'm glad to say I'm one of the new generation who buy vinyl exclusively as listening format. My stereo aside from turntable is all equipment from mid to late 80's that I inherited from the older generations, and my car is not equipped with CD player so the format is less interesting to me.
I got into vinyl the same time I got into more punk related bands. I've listened to metal for years, but only in the last year and a half have I gotten more into the punk scene. A lot of bands in punk release splits or ep's on 7'' vinyl format, or LP-only albums so it seemed logical to invest in a working turntable and buy more from this format because a majority of releases I was getting into had no alternatives. It spilled over to metal, which i was buying mostly tapes because of my car lacking a CD player making the tape format more preferred because I could play them during my job as a pizza driver. This still is the reason as I have no CD player, and at home why bother with the inferior of plastics and instead play mostly vinyl. Due to this I spend more for the format, but this I do not mind because I like the sounds and quality, and the larger arts/lyric sheets.
I personally love the format of vinyl over cd any day, and I've seen a rise in its popularity among both metal heads and general music fans, so i guess one can hope this trend will continue to preserve it. There are CD collectors, and while I'm not as fond of this type of collecting, i guess to each their own.
Anyway, this is my 2 cents, apologize for the long texts.
