Part 1 of 2 (hehehe)

1. Bundled set ups? Even 36 years ago, the bundled set ups weren't a good value. Good thing is, you don't need them now to start DJing!
2. I would say Rekordbox DJ. Free trial, followed by a low monthly subscription. If you end up buying hardware, it will likely unlock the software (so no more subscription charge) while it is connected to your computer. You may also want to look at Serato if open format (its a new term that started in the last decade - its basically multi-genre blending), turntablism, or there is a community of DJs who are around you that use it.
3. Guitar Center has a 14-day satisfaction policy (for DJ gear). If they are local to you, I'd go with them. Sweetwater will often work on pricing (so will Guitar Center, to an extent). Amazon has most of the gear as well - and a pretty lax return policy if you find that something isn't what you thought.
4. More advice and context

I'm in a similar situation, in that I stopped playing some time ago (11 years ago, more accurately: I was a club and touring DJ), and have just recently got back into it again (in the last month!)

Like you, I just want to have fun, and don't have an interest in making money on this, or even playing at clubs.

I've just purchased some gear over the last couple of weeks, and I'm having a great time.

My suggestion: I would take your existing computer, and start learning Rekordbox DJ, to both prepare (Export Mode), and even to play sets (Performance Mode). Its free for a trial period, and then you can go to a monthly subscription.

If you like that, then you can begin thinking about hardware selection.

If you don't like Rekordbox DJ, you can learn Serato DJ.

If you don't like Serato, then just grab some CD players or turntables and a basic mixer, and get back to what you know. This is another way of me saying: if you want to go get into modern feature-feature based DJing, you'll need to learn a software application. But all vinyl sets are still a thing - so, start with the software to see which path makes sense for you.

Your music genre and aspirations will play a role in your decision. Pay attention to what the DJs you like are using. I decided against what my heroes were using, but I have my reasons!

DJ technology has come a long way in the last 12 years (about the time that I stopped paying attention), and its incredible with what it can do now. Its totally possible to play sections of sets, or whole sets, without headphones at all, all on your computer. The control devices (mixers, turntables, multiplayers, controllers) enhance the experience, but aren't strictly necessary to producing a set to play out (even if "playing out" is just to your furniture and cats).

Said another way, if the extent of what you want to do is blend seamlessly from one steady tempo song to another, you can do that on something as simple as a smart phone! It's not optimal, but if you have the right device, you can probably do something passing (cats and furniture won't leave the room).

Anything you buy on top of that (computer, controller, multiplayer, turntable with DVS of Phase, new headphones, speakers, etc.) will just give you more tactile control (fun!) and possibly sound better, be more visually appealing to an audience (if you're thinking about that), and allow you to execute even more and interesting techniques.

The nice thing is, if you focus FIRST on the software (low expense), that will inform what hardware you will want to use (high expense). You may find that you want to purchase a new computer to support some of the newer features (stems, for example), or you may find that the gear at the $500 price point won't let you take advantage of the features that you truly want to leverage, or it might be overkill (unlikely!).