Xenologer 241 is pretty cheap actually.

Xenologer This deck was less than $200 before the extreme raise of the price of Inkmoth Nexus and some of the other cards like Skithiryx, the Blight Dragon. Last year Inkmoth was about 8-9$ and Skithiryx about 6. But you're right, I should quit the budget tag by the moment....

I played a deck like this in standard it was very fun and very effective. I played Lashwrithe and Liliana of the Dark Realms with Whispering Specter to make my opponent discard their entire hand on turn 4. might be a but too slow/fragile for modern though.

I'm not sure about Phyrexian Arena, I could see it winning games, but I also see it slowing you down too much. I think it's pretty bad in multiples so I would cut at least 1. I also think you're running too many Go for the Throat. While it's good against most decks, it's terrible against affinity.

I'd also run more targeted discard, I recommend Duress for a budget option.

Ok, so I saw this deck recently and decided to buy this bad boy. I got most of it at the local magic store today and ordered the remainder from tcg player. The only card I have a problem with is mutagenic growth, I don't like the idea of sacrificing 2 life all that much, the question is what do I replace it with?

Vampire's Bite but Mutagenic Growth is way better because it's free.

Maybe throw in a playset of Phyrexian Obliterators? Obvoisly that would mean taking out some cards, so take out Two phyrexian cruscaders and two plague stingers to make room?

but thats just me loving Phyrexian obliterator