There are other, more reliable suppliers than ebay, AliExpress and Amazon.  Below are some I have found useful.

When searching for components, Octopart is your friend.  Searching on a part number will show stock and pricing at major suppliers.  The Octopart BOM Tool is extremely useful.   Enter your BOM (Bill of Materials) for a project and it will show your the price for any build quantity (selecting from a list of suppliers you specify), items in short supply and can even suggest alternative parts.

Tayda Electronics

Tayda is located in Thailand, with some US warehousing.  They have a wide range of components and hardware.  I don't recommend them for onesy-twosy items but the shine for stocking up.  They feature quality products at extremely good prices.

Jameco Electronics

A US supplier with great prices.  They have a good range of parts, including some economical "Jameco ValuePro" parts, and they frequently have close-out items are large discounts.  Their retail location is in Belmont California, but it is for pickup only.  You must order ahead on-line or by phone.

MPJA (Marlin P. Jones Associates)

Located in West Palm Beach, Florida, MPJA has many pcb breakout boards, modules, power supplies and the like rather than a focus on components.  They sell a lot of Chinese imports with good documentation.

LCSC

LCSC is the Chinese equivalent of Digikey and is associated with JLCPCB (Chinese PCB fab).  The have nearly all of the western parts available at distributors like Digikey plus many otherwise difficult-to-obtain Chinese components at incredible prices,  Their datasheets are often in Chinese but Googling the part number will often retrieve an English datasheet.

Mainline Distributors

These are the big boys of electronic supplies.  They carry everything and you can be sure of the quality when purchasing from these vendors.  All of these have similar product lines.

Digikey

Mouser

Newark Electronics

RS

Arrow