A cheap magic the gathering deck?

22 Mountain

3 Spinerock Knoll (0.50)

4 Magma Spray

4 Incinerate

4 Ashenmoor Gouger

3 Puncture Blast

4 Volcanic Fallout (1.50)

4 Stomping Slabs (Banefires are 9 bucks!)

4 Boggart Ram-Gang (1.00)

4 Deus of Calamity (3.50 [or for 5.00, Siege-Gang Commander])

4 Flame Javelin (1.75)

SB

4 Vexing Shusher (2.00 for the release event version)

3 Manabarbs (1.00)

4 Pyroclasm (1.50)

4 Everlasting Torment (3.00)

So the big splurges are your big fatty rare (still cheaper than Demigod of Revenge, though the Demigod is better) and the Everlasting Torments. I played four of these at the most recent T2 FNM's and they helped against every deck that used Burrenton Forge-Tender, Runed Halo, Story Circle, Kitchen Finks, etc. My version played a few more power pieces, but the list is very similar. I won 2 of the 3, so hopefully that gives you some insight. My meta-game requires me to use Manabarbs and Shushers because of the prevalence of 5-Color Control and people playing 10+ counterspells in Faeries. If you have a load of burn, play Dragon's Claw or a red hoser instead.

If you're going to make a Standard deck for $20-50, that rules out Faeries, B/W Tokens, and several other popular decks.

My suggestion is to go for raw burn. Something like this:

20 Mountain

4 Volcanic Fallout

4 Hellspark Elemental

4 Hell's Thunder

4 Flame Javelin

4 Shock

4 Incinerate

4 Beacon of Destruction

4 Furnace of Rath

4 Pyroclasm

4 Puncture Blast

Sideboard:

3 Magma Spray

3 Firespout

3 Lash Out

3 Vexing Shusher

3 (Metagame Slot - this is for fighting whatever's popular in your area.)

The Furnace of Rath is the spell that really makes this deck devastating. There's so much creature-based burn that you should be able to keep the board clear until you can drop a Furnace and then start swinging out with Hellsparks and Hell's Thunder. There's no killer rares in this deck, so it shouldn't be more then ~$30, and that's a high estimate.

The burn looks decent, but I'm a little skeptical what it would be able to do against a mad fast elf deck or something. I wouldn't play 4 beacons. I have two in my burn deck, and I find that it works out okay.