Welcome. The two lowest priced dealers in the US are SD Bullion and Silver.com. APMEX is generally a rip-off if the product is available at the other two.
Silver.com is owned by JM Bullion, but is significantly cheaper on most products. Why would JM Bullion operate a separate online dealer with lower prices than its existing store? It's complicated, but it has to do with price strategy, price discovery (learning the equilibrium price of a given product), and scooping up more search results on Google and so forth. JM Bullion bought the domain "Silver.com" for nearly a million dollars a few years ago to execute their strategy. Maybe @LawrenceChard can chime in with thoughts on this kind of dealer strategy.
The choice between SD Bullion and Silver.com often comes down to shipping charges, because they'll be very close on price (and much cheaper than everyone else). Silver.com is often nominally cheaper, but the hitch is that they charge for shipping on all orders below $3,000. This is a much higher threshold than most dealers – it's usually set around $200. SD Bullion ships free for orders above $199. On the other hand, Silver.com only charges $5.95 for shipping, on those orders under $3,000, which is about the lowest shipping charge in the industry. SD Bullion charges $9.95, but that's only if your order is under $199.
So when they're close on price, Silver.com will win on orders under $199. It gets complicated on orders above that, and you just have to do the math as needed. On orders over $3,000, Silver.com usually wins.
Those two are where I recommend you buy all your bullion, if possible. They're virtually never beat by any other dealers on anything they actually have in stock. In fact, I can't remember a single time they've been beat, and I have lots of saved price data in spreadsheets. The exception is when a dealer has a sale, of course, some sort of promo. Those can be very handy, especially for beginners like yourself, since many of the best promos are specifically for new customers. I got a very nice 10 oz silver bar at spot price from SilverGoldBull last year, because I was a new customer there.
So keep an eye out for promos. Subscribe to dealer newsletters and emails and you'll get offers. They all do it.
The only time to deviate from SD Bullion or Silver.com or a promo is for something they just don't have in stock. That's when you go to JM Bullion, BOLD Precious Metals, Bullion Exchanges, Gainesville Coins, SilverGoldBull, et al. APMEX is your last resort. They're almost always a rip-off, but they also have the widest selection, and it's possible they'll be the only dealer stocking a 2 oz 2017 Silver Libertad or some such.
Note that if you're stacking and not collecting, you'll never need to venture to overpriced dealers just because they have one specific thing that you want. If you're stacking, you can be more disciplined and patient. SD Bullion and Silver.com will always have the major products in stock, at least in normal market conditions. Right now there's a shortage everywhere, but they still have the flagship bullion products like the major national mint stuff (Eagles, Maple Leafs, Britannias, etc). Bars are mostly out of stock everywhere, with maybe one or two choices per size at major dealers, or zero stock of sizes like 1 oz.
Also note that if you're in North Texas, DFW, etc and you buy from JM Bullion or Silver.com, it's not actually local in the physical sense. It's not coming from a local facility or fulfillment center. It's coming from Las Vegas. JMB doesn't do their own fulfillment. They farm that out to A-Mark, a major behind-the-scenes precious metals distributor with operations in Vegas. My SilverGoldBull order came from Vegas, so they probably use A-Mark as well (I think SilverGoldBull is based in Canada). SD Bullion does their own fulfillment. I think they're in Michigan.
There's also Texas Precious Metals somewhere south of you. They have a good reputation in the industry, and they're the only dealer I know of that does limit orders, where you can trigger automatic purchases based on spot price movement or something.
Gainesville Coins is good and they have lots of unique inventory with trident and sea themed designs.
BOLD Precious Metals is pretty good, and carries a lot of fancier bullion, Marvel superhero stuff and so forth. The premiums on that will be steep though.
Golden State Mint has unique inventory, and not too expensive. They're one of the few that carry a lot of the Silver Shield series, like the Freedom Girl rounds – those are great.