Matt
You've gotten a lot of good advice, but I'm going to go against the grain.
I have a Delta 43-375, so I know the shaper you are looking at.
-For a hobbiest, a 1/4hp feeder will probably do most everything you will need. Yes ,it is not a "big" feeder, but it will do it. You start doing more production line moulding, or big heavy architectural work, then yes, it will be too small, but so too will be the shaper.
- The OEM router collet adapter is expensive simply because they were not shipped OEM with the machine. They had to be ordered. Their availability is very limited. The good news is that I have one and their really not very nice at all. The link you have been provided is a much, much, nicer adapter than OEM.
- The 3/4" spindle should be easy to get, and not that expensive. An OEM 1" spindle for your machine can cost big $$$$. Last time I saw one for sale it went for close to $600.00. You won't need it though.
- For the majority of cuts you may need to do, Delta made Cutters. They made them by the zillions and they can be had for $30-$50 bucks all over eBay. They won't last in a production environment, but they will last you for years.
-The 1/2" router collet adapter is easy to find. The link was already provided.
- If it really comes with no spindles, that's odd??? How was the person using it? Definitely something to factor in, because that's at least a $100.00 for a 3/4" spindle.
- Don't bother with buying a 1/2" spindle. It's too limiting.
- Parts for this shaper are available all over eBay and Craigslist. The Delta Shapers were made for over 50 years, and many of the parts are identical. They even have the same part numbers. There isn't a single replacement part you cannot find for that shaper.
- The fences for the Delta Shapers are uhmmm, junkie. All of them. Plan on either making a fence, or buying a fence. Fences can big $$$$
-Sometimes you can luck into good deals on the Delta's, like folks have stated, sometimes not. But, you're not going to buy a new shaper, with feeder, that is better than that Delta for the same money. It's not going to happen.
-It does seem a little high, lack of spindle(s), so adjust your offer if you decide to go for it.
My .02 fwiw.
"The first thing you need to know, will likely be the last thing you learn." (Unknown)