Welcome to R2R...
You can do this in 2 different ways. One will be to get something like the Red sea or Water box package tanks but you still have to buy the skimmer and lights. The other way is to build your own with buying each components individually. I can try to give you a budget idea with each of them...
Main tank- 75G or
https://www.reef2reef.com/threads/75-gallon-and-custom-stand.426644/
https://www.marinedepot.com/AquaMax...lar_Aquariums-AquaMaxx-UJ94563-FIAQRA-vi.html
Or Aqueon tanks and drill it by yourself (Cheaper)
Dont go over $400
Stand- Build your own if you can save some money $250
Sump- Used or new with skimmer
https://www.bulkreefsupply.com/60-filtration-system-somatic.html $280
Lights-https://
www.bulkreefsupply.com/ati-36-t5-dimmable-sunpower-fixture.html $560 (a used one will be lesser within $300)
Skimmer- Used ones for $200
Plumbing-$125
Rocks and sands-$150
Power heads- mp10 used $125 x2 = $250 or Tunze (
https://www.reef2reef.com/threads/e...ch-tunze-etc-need-fishing-kayak-funds.428022/)
Heater-https://
www.bulkreefsupply.com/eheim-jager-trutemp-aquarium-heater.html 200W EHEIM JAGER AQUARIUM HEATER $27.54
Return pump- Siecce or Eheim pumps for $125
RO/DI setup-$150 BRS
https://www.bulkreefsupply.com/4-stage-value-ro-di-system-bulk-reef-supply.html
ATO- Tunze ATO 3155. $115 used (
https://www.reef2reef.com/threads/e...ch-tunze-etc-need-fishing-kayak-funds.428022/)
So, this will add upto $2500 total and most of the equipment you can even use for your future builds too. If you go all used equipment then it will can cost you less than $2000 too but always buy quality equipments as they will save a lot of money in long run. I added some link for your equipments from the sale thread here as well as from other websites for your reference. Most of my equipments are used ones and they are working like champs since last 3 years or more. Hope this helps you. Let us know if you need any further information.
Happy reefing.