First,
My instinct is to put in a buy order for slightly less than the current price and give it a 60-day limit and expecting it will get there in the next couple days. But what numbers should I be looking at to make this decision? Like, do you just look at a graph of values over the past month to get a feel for what the highs and lows are and how often it swings? It's at 87.9 now and was at 87 or below three times in the past month so I figured I might be safe asking for 87 (or 87.01 if that would be more likely to get me a sale than people who put in 87). Or 87.5 if I wanted to buy sooner. Or do you look at the NAV? Or do most buy-and-hold people just do a market buy? Putting in a limit makes me feel like I might be making it too complicated but it seems silly to not try to get a lower price when it varies by +/- 50 cents just over the course of the day, y'know?
1) You should just buy the asset if you want it in your portfolio and not screw around with trying to get a better price. Yes, if you put a bid just below the current market, there's a good chance you'll get filled. However, there's also a chance that asset rallies for awhile and you don't get filled at all. Because the asset is likely to generate returns over time, your below market bid has a negative expected value. You can think of it this way: there's a high probability that you save a little money, and low probability that you miss out on a lot of money. On average, the bet is a loser.
2) Never leave a multi-day order outstanding. Basically, you're just giving away optionality. If the bottom ever falls out of the market due to some unforeseen event, your bid is just free money to someone else.
3) As a general practice. It's good to use limit orders, if for no other reason than to be clear on what you're paying. if the current market is 87.85/87.90, you can even put in a limit order for 88.00 and you'll get filled at the best level. In this case, probably 87.9 or better. For highly liquid products, it doesn't matter much whether you use a market or limit order, but it's a good habit to get into so that when you run into an illiquid product, you don't pay an unexpectedly high price.