I wouldn't consider it silly! I'm a cosplayer.. been cosplaying since 2007. I would definitely not claim to be an amazing cosplayer because there are people that are far more talented in this area than I am, haha.
In terms of seeing really good cosplays versus trying to put your own together, it might be more difficult (or easier) than you think. From personal experience, I think that homemade costumes--that is, crafting armor, stitching fabrics together / hand-stitching clothes, making props, getting the correct proportions, etc--come out better than store-bought costumes, and I say that because there is always going to be a level of detail that store-bought costumes will never achieve, but handmade costumes can at least attempt it. The amount of money you're willing to spend for a costume is also extremely important. If you want a good costume, expect it to cost a minimum of $300. I can tell you that I've spent at LEAST $2,500 for my costumes over the years, and I don't even consider my costumes to be great.
I am personally a horrible seamstress; I've broken the last two sewing machines I've owned, and hand-stitching anything bigger than a fabric tear is too much of a pain. Though it makes things more expensive, you can do what I (and many others) do: purchase separate parts of the costume, adjust and "editing" it to your preferences.
Say, for example, I want to cosplay as the Ryan Reynolds movie-version of Hal Jordan's Green Lantern.

The way I would go about putting this costume together is first establishing my budget and how much I want to spend on this costume (let's say I'm not giving myself a deadline, that makes it much easier, haha). After establishing a budget, I would do research on all of the separate parts of the costume: the body suit, the boots, the gloves / gauntlets, the eyemask, and the GL ring. I would search for reliable retailers, seamstresses, and crafters, searching for the best deal for good quality items (as pertaining to my budget).
I would have the eyemask handmade and fit to my facial dimensions so the mask wouldn't bulge or jut out at strange angles, but would instead fit firmly and tightly on my face. I would request a custom made body suit for the body, boots, and gloves (as they are all included in the suit), probably a 4-way stretch milliskin fabric for comfort and stretch ability; the suit would be the most expensive, and for a custom design and intricate detail such as this, I would guess between $400-550. The ring, I would purchase at Toys 'R Us because they sell a "movie version GL ring, and it's more or less the same thing. I would purchase ice blue contact lenses for that extra added effect (my eyes are hazel, so I would need the contacts to get that BRIGHT blue look).
For the hairstyle, I would either get a wig or style my hair like Reynolds does in the movie.
I hope this is somewhat along the lines of what you were looking for, haha.