If you need an oven for professional use: buy it
If you need an oven fore some SMD board: elektor oven ( or similar)
If you want to test, try a 20 Euro oven , you can have good result even without electronic ( just to see what happens)
There are good inexpensive toaster oven with a fan
You can buy TWO low cost ovens, take heaters from one oven and double heathers on the other.
If you do not like mains voltage, please ask for help from an experienced technician.
Paolo