When it comes to Halloween decor, the best deals can sometimes come from unexpected places. Sure, Walmart has their Halloween Cobwebs for $4.99 and Party City has their Giant White Stretch Spider Webs on sale for $3.99. But you can also buy quality cobwebs at Dollar General for around $1 and about the same price at Dollar Tree. What you spend at Walmart or Party City, you can get more cobwebs for less at other places.
Spirit Halloween is a fun place to visit and has an amazing selection! But if you are on a budget this Halloween, they might not be the place to get what you need. Once again, I am going to mention Party City. We don't have one in my town (which is a bummer) but the prices are great! You can get wall cutouts for less than $1! Even the classic jointed skeleton (I might just get that this year!) is at a cheap price of $5!
If you're looking for major decorations like ghosts for the yard or want a lighted curtain like you've been seeing, then your best bet is to check out Lakeside Collection. They have a Lighted Halloween Curtain for $9.95, which is a great deal to me! You will find something like it online for upward to $20! If you're looking for a 3-foot Ghost trio to set outside, then you can try FrightCatalog's Ghostly Lawn Set for $24.99.
For larger outdoor items, Spirit Halloween or even FrightCatalog, if you don't mind spending a small fortune. I like to keep it simple. So I don't know what are deals and what isn't when it comes to those.
I don't hold Halloween parties. Its just between me, Mom, Twin, and sometimes Dad, if he happens to be off that night. So I wouldn't be any help as far as party supplies go, though I can point you into a direction. Don't discount the dollar stores (i.e. Dollar General, Family Dollar, Dollar Tree) for supplies. You're only going to be using them for one night, right? Get enough for extras, and call it a day.
But I must warn you on "too good to be true" deals. If you see a deal for, lets say, a dozen bags of table confetti at only $10 for the dozen, read the reviews for the product. These places that sell items like that tend to have amazing prices but the item's quality could be severely misrepresented. If its "too good to be true", it usually is.